Open actionable advisories and recorded vendor fixes. This public package view has no inventory attached and cannot establish whether your deployment is affected. A vendor fix never resolves your finding; verify your installed version and the source guidance.
Open advisories
23 actionable advisories, newest first. Withdrawn advisories and news are excluded. Coverage is partial.
An uncontrolled-resource-consumption vulnerability (CWE-400) in the Twisted HTTP/2 server lets any unauthenticated remote client exhaust server CPU over a single connection. A client that sends a request header block with `END_STREAM` and then immediately resets the stream makes the server route and render the request before it processes the reset. Reset streams are freed and never count against the concurrent-stream limit, and no reset-rate limiter exists, so the pattern can be repeated at line rate on one connection. This is the HTTP/2 Rapid Reset class, CVE-2023-44487. Details For one received segment the h2 events are processed in order in `H2Connection.dataReceived`. A `HEADERS(END_STREAM)` followed by `RST_STREAM` yields `RequestReceived`, `StreamEnded`, then `StreamReset`, so the request is dispatched and rendered on stream end before the reset is handled: ```python src/twisted/web/_http2.py (H2Connection.dataReceived) for event in events: if isinstance(event,…
Recommended action: Upgrade to 26.10.0rc1 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
`twisted.names.dns.DNSDatagramProtocol`, the UDP transport used by twisted's DNS client (`twisted.names.client.Resolver`, `createResolver`, and anything built on it, including MX lookups in `twisted.mail`), accepts a DNS response for a pending query solely on the basis of the 16-bit transaction ID matching. It never checks that the response actually originated from the server the query was sent to. Any host that can deliver a UDP packet to the resolver's listening port with the correct transaction ID can inject a forged answer, independent of the real server's address. This is a materially weaker defense than standard DNS resolver practice (transaction ID plus source-address validation, typically also source-port rotation), and enables off-path DNS response spoofing / cache poisoning. Details `DNSDatagramProtocol.datagramReceived` (`src/twisted/names/dns.py`, line 3350) is: ```python def datagramReceived(self, data, addr): """ Read a datagram, extract the message in…
Recommended action: Upgrade to 26.10.0rc1 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
An infinite-loop vulnerability (CWE-835) in the Twisted IMAP4 server lets an authenticated client freeze the whole process with one small command. twisted.mail.imap4.parseNestedParens reads an IMAP literal size with int() and never rejects a negative value. A negative size such as {-100} drives the parser cursor negative, and because a negative Python index wraps around the end of the string instead of raising, the scanning loop never terminates. It runs synchronously on the single-threaded reactor, so one SEARCH command holds the reactor at full CPU forever and every other connection stops being served. Details Meeting an inline literal, parseNestedParens reads the size between the braces and advances the cursor past the body: int(b"-100") is -100, so i goes negative; the loop condition i < len(s) stays true and s[i : i + 1] on a negative index never raises, so the cursor cycles forever. The literalStringLimit guard only covers the synchronizing-literal continuation path,…
Recommended action: Upgrade to 26.10.0rc1 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
An unbounded-buffer vulnerability (CWE-770) in the Twisted words IRC server lets any unauthenticated remote client exhaust server memory. twisted.words.protocols.irc.IRC.dataReceived appends every received byte to a per-connection buffer and only removes data at a line feed, with no maximum length. Because IRC is a plain Protocol and not a LineReceiver, one connection that streams bytes without a line feed grows the buffer without bound and drives the whole single-threaded process to out-of-memory, dropping every user at once. The twistd words server inherits the method unchanged through IRCUser, and the data is buffered before any authentication. Details IRC.dataReceived keeps everything up to the last line feed in self.buffer: With no line feed in the data, lines.pop() returns the entire accumulated content to self.buffer, so it grows by every chunk and is never bounded; IRC defines no MAXLENGTH, no lineLengthExceeded, and no timeout, so the connection is never closed. The…
Recommended action: Upgrade to 26.10.0rc1 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
An allocation-without-limits vulnerability (CWE-770) in the Twisted conch telnet transport lets any unauthenticated remote peer exhaust server memory over a single connection. When the peer opens a telnet subnegotiation with IAC SB and then streams bytes without ever sending the IAC SE terminator, every byte is appended to a per-connection buffer that has no maximum length. The buffer persists across reads and is released only on the terminator the attacker withholds, so it grows without bound until the process is killed. Details The option-negotiation state machine in Telnet.dataReceived enters the subnegotiation state on IAC SB and sets an empty command list. In that state every non-IAC byte is appended to the list with no length check: self.commands is an instance attribute that persists across dataReceived calls and is deleted only when IAC SE completes the subnegotiation. Negotiation runs at the transport layer before authentication, and the bytes are consumed inside…
Recommended action: Upgrade to 26.10.0rc1 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
An allocation-without-limits vulnerability in the Twisted XML element stream lets any unauthenticated remote peer exhaust server memory over a single stream. When the peer opens a container element and streams child elements without ever closing the container, every element is materialised into an in-memory tree with no limit on depth or child count. An element is released only when its end tag arrives, so a container the attacker never closes retains everything beneath it until the process is killed. Details In ExpatElementStream.onStartElement, each start tag appends a new element to the current element's children and descends into it, with no depth or child-count check: An element is emitted and dropped only when its end tag arrives while it sits directly under the document root, so a container that is never closed keeps every child beneath it. The transport XmlStream.dataReceived feeds bytes to self.stream.parse(data) with no size limit, and in XMPP the stream is parsed…
Recommended action: Upgrade to 26.10.0rc1 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
An incomplete header-value validation (CWE-444) in the Twisted HTTP server lets a bare carriage return or line feed in a header value hide a following header from the parser. twisted.web.http.HTTPChannel.headerReceived rejects a NUL byte in a header value but not a bare CR or LF, even though RFC 9110 section 5.5 requires a recipient to reject all three. Because the channel splits requests only on CRLF, a value carrying a bare LF and a second header arrives as one line, so the second header is folded into the value and the request is framed with no body. A front-end that treats the bare LF as a line terminator frames the request differently, and the disagreement lets an attacker smuggle a request past it. This is an incomplete fix of the earlier Twisted request-smuggling advisories, which guarded the NUL sibling of this exact check. Details headerReceived splits a header line on the first colon, strips space and tab from the value, and validates it with a single test that…
Recommended action: Upgrade to 26.10.0rc1 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
Details The twisted.names module is vulnerable to a Denial of Service (DoS) attack via resource exhaustion during DNS name decompression. A remote, unauthenticated attacker can exploit this by sending a crafted TCP DNS packet containing deeply chained compression pointers. This flaw bypasses previous loop-prevention logic, causing the single-threaded Twisted reactor to hang while processing millions of recursive lookups, effectively freezing the server. --- Technical Details The main issue is in twisted.names.dns.Name.decode. A visited set was added in 2011 (commit e11cd82) to prevent infinite loops, but there is still no limit on the number of pointer dereferences per message. Also, the visited set is reset for each Question record. Because DNSServerFactory handles every record in QDCOUNT without checking them, an attacker can add thousands of questions that all refer to the same long chain of pointers. This makes the parser repeat a complex and unnecessary search. --- PoC ---…
Recommended action: Upgrade to 26.4.0rc2 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
The twisted.web.util.redirectTo function contains an HTML injection vulnerability. If application code allows an attacker to control the redirect URL this vulnerability may result in Reflected Cross-Site Scripting (XSS) in the redirect response HTML body. Details Twisted’s redirectTo function generates an HTTP 302 Redirect response. The response contains an HTML body, built for exceptional cases where the browser doesn’t properly handle the redirect, allowing the user to click a link, navigating them to the specified destination. The function reflects the destination URL in the HTML body without any output encoding. If an attacker has full or partial control over redirect location due to an application bug, also known as an “Open Redirect”, they may inject arbitrary HTML into the response’s body, ultimately leading to an XSS attack. It’s worth noting that the issue is known to maintainers and tracked with GitHub Issue#9839. The issue description, however, does not make any…
Recommended action: Upgrade to 24.7.0rc1 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
The HTTP 1.0 and 1.1 server provided by twisted.web could process pipelined HTTP requests out-of-order, possibly resulting in information disclosure. PoC 0. Start a fresh Debian container: 1. Install twisted and its dependencies: 2. Run a twisted.web HTTP server that echos received requests' methods. e.g., the following: 3. Send it a POST request with a chunked message body, pipelined with another POST request, wait a second, then send a GET request on the same connection: 4. Observe that the responses arrive out of order: Impact See GHSA-xc8x-vp79-p3wm. Further, for instances of twisted.web HTTP servers deployed behind reverse proxies that implement connection pooling, it may be possible for remote attackers to receive responses intended for other clients of the twisted.web server.
Recommended action: Upgrade to 24.7.0rc1 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
Twisted is an event-based framework for internet applications. Prior to version 23.10.0rc1, when sending multiple HTTP requests in one TCP packet, twisted.web will process the requests asynchronously without guaranteeing the response order. If one of the endpoints is controlled by an attacker, the attacker can delay the response on purpose to manipulate the response of the second request when a victim launched two requests using HTTP pipeline. Version 23.10.0rc1 contains a patch for this issue. Details There's an example faulty program: When two requests for /first and /second are sent in the same order, the second request will be responded to first.
Recommended action: Upgrade to 23.10.0rc1 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
When the host header does not match a configured host, twisted.web.vhost.NameVirtualHost will return a NoResource resource which renders the Host header unescaped into the 404 response allowing HTML and script injection. Example configuration: Output: This vulnerability was introduced in f49041bb67792506d85aeda9cf6157e92f8048f4 and first appeared in the 0.9.4 release.
Recommended action: Upgrade to 22.10.0rc1 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
Impact Twisted Web is vulnerable to request smuggling attacks: 1. "When presented with two content-length headers, Twisted Web ignored the first header. When the second content-length was set to zero this caused Twisted Web to interpret the request body as a pipelined request. According to RFC 7230 Section 3.3.3#4, if a message is received with multiple content-length headers with differing value, then the server must reject the message with a 400 response." (Jake Miller of Bishop Fox Security) 2. " When presented with a content-length and a chunked encoding header, the content-length took precedence and the remainder of the request body was interpreted by Twisted Web as a pipelined request. According to RFC 7230 Section 3.3.3#3, if a message with both content-length and chunked encoding is accepted, transfer-encoding overrides the content-length." (Jake Miller of Bishop Fox Security) 3. ~"Twisted should not allow BWS between the filed-name and colon." (ZeddYu Lu)~ closed in 9646 4.…
Recommended action: Upgrade to 20.3.0 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
The Twisted Web HTTP 1.1 server, located in the twisted.web.http module, parsed several HTTP request constructs more leniently than permitted by RFC 7230: 1. The Content-Length header value could have a + or - prefix. 2. Illegal characters were permitted in chunked extensions, such as the LF (\n) character. 3. Chunk lengths, which are expressed in hexadecimal format, could have a prefix of 0x. 4. HTTP headers were stripped of all leading and trailing ASCII whitespace, rather than only space and HTAB (\t). This non-conformant parsing can lead to desync if requests pass through multiple HTTP parsers, potentially resulting in HTTP request smuggling. Impact You may be affected if: 1. You use Twisted Web's HTTP 1.1 server and/or proxy 2. You also pass requests through a different HTTP server and/or proxy The specifics of the other HTTP parser matter. The original report notes that some versions of Apache Traffic Server and HAProxy have been vulnerable in the past. HTTP request smuggling…
Recommended action: Upgrade to 22.4.0 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
Impact Twisted web servers that utilize the optional HTTP/2 support suffer from the following flow-control related vulnerabilities: Ping flood: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-9512 Reset flood: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-9514 Settings flood: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-9515 A Twisted web server supports HTTP/2 requests if you've installed the http2 optional dependency set. Workarounds There are no workarounds. References https://github.com/Netflix/security-bulletins/blob/master/advisories/third-party/2019-002.md For more information If you have any questions or comments about this advisory: Open an issue in Twisted's Trac
Recommended action: Upgrade to 19.10.0 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
Impact The Twisted SSH client and server implementation naively accepted an infinite amount of data for the peer's SSH version identifier. A malicious peer can trivially craft a request that uses all available memory and crash the server, resulting in denial of service. The attack is as simple as nc -rv localhost 22 < /dev/zero. Patches The issue was fix in GitHub commit https://github.com/twisted/twisted/commit/98387b39e9f0b21462f6abc7a1325dc370fcdeb1 A fix is available in Twisted 22.2.0. Workarounds Limit access to the SSH server only to trusted source IP addresses. Connect over SSH only to trusted destination IP addresses. References Reported at https://twistedmatrix.com/trac/ticket/10284 Discussions at https://github.com/twisted/twisted/security/advisories/GHSA-rv6r-3f5q-9rgx For more information Found by vin01
Recommended action: Upgrade to 22.2.0 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
Impact Cookie and Authorization headers are leaked when following cross-origin redirects in twited.web.client.RedirectAgent and twisted.web.client.BrowserLikeRedirectAgent.
Recommended action: Upgrade to 22.1.0 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
Twisted before 16.3.1 does not attempt to address RFC 3875 section 4.1.18 namespace conflicts and therefore does not protect CGI applications from the presence of untrusted client data in the HTTPPROXY environment variable, which might allow remote attackers to redirect a CGI application's outbound HTTP traffic to an arbitrary proxy server via a crafted Proxy header in an HTTP request, aka an httpoxy issue.
Recommended action: Upgrade to 16.3.1 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
In Twisted Web before 20.3.0, there was an HTTP request splitting vulnerability. When presented with two content-length headers, it ignored the first header. When the second content-length value was set to zero, the request body was interpreted as a pipelined request.
Recommended action: Upgrade to 20.3.0 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
In Twisted Web through 20.3.0, there was an HTTP request splitting vulnerability. When presented with a content-length and a chunked encoding header, the content-length took precedence and the remainder of the request body was interpreted as a pipelined request.
Recommended action: Upgrade to 20.3.0 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
Python Twisted 14.0.0 trustRoot is not respected in HTTP client
Recommended action: Upgrade to 14.0.1 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
In words.protocols.jabber.xmlstream in Twisted through 19.2.1, XMPP support did not verify certificates when used with TLS, allowing an attacker to MITM connections.
Recommended action: Upgrade to 19.7.0rc1 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.
In Twisted before 19.2.1, twisted.web did not validate or sanitize URIs or HTTP methods, allowing an attacker to inject invalid characters such as CRLF.
Recommended action: Upgrade to 19.2.1 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.