net-imap vulnerable to command Injection via "raw" arguments to multiple commands

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

5.8 · CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-42257: 0.43% estimated exploitation activity in the next 30 days; percentile 37.21 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Several Net::IMAP commands accept a raw string argument that is sent to the server without validation or escaping. If this string is derived from user-controlled input, it may contain contain CRLF sequences, which an attacker can use to inject arbitrary IMAP commands. Details Net::IMAP's generic argument handling, used by most command arguments, interprets string arguments as an IMAP astring. Depending on the string contents and the connection's UTF-8 support, this encodes strings as either a atom, quoted, or literal. These are safe from command or argument injection. But the following commands transform specific String arguments to Net::IMAP::RawData, which bypasses normal argument validation and encoding and prints the string directly to the socket: #uidsearch, #search, #uidsort, #sort, #uidthread, #thread when criteria is a String, it is sent raw #uidfetch, #fetch when attr is a String, it is sent raw when attr is an Array, each String in attr is sent raw #uidstore, #store…

Published by the source

4 May 2026, 22:04 UTC

Last modified by the source

17 Jun 2026, 19:45 UTC

Source last checked

26 Oct 2026, 15:52 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-hm49-wcqc-g2xg

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# Patch Next advisory brief: CVE-2026-42257

Advisory: net-imap vulnerable to command Injection via "raw" arguments to multiple commands
IDs: CVE-2026-42257, GHSA-hm49-wcqc-g2xg
Record: https://patchnext.com/advisories/cve-2026-42257 (revision 1, source checked 26 Oct 2026, 15:52 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: net-imap 0.6.4, 0.5.14, 0.4.24. A vendor fix does not mean a deployment is fixed.

## Affected components
- RubyGems net-imap: affected >= 0.6.0, <= 0.6.3; >= 0.5.0, <= 0.5.13; <= 0.4.23; fixed in 0.6.4, 0.5.14, 0.4.24

## Suggested inspection (read-only)
- RubyGems net-imap: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on net-imap.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-hm49-wcqc-g2xg (GitHub-reviewed advisory GHSA-hm49-wcqc-g2xg lists affected ranges: RubyGems net-imap >=0.6.0 =0.5.0 =0 <=0.4.23)

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