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Medium, CVSS 5.9amended

Prefix Truncation Attack against ChaCha20-Poly1305 and Encrypt-then-MAC aka Terrapin

CVE-2023-48795GHSA-45x7-px36-x8w8

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (golang.org/x/crypto 0.17.0, 0.0.0-20231218163308-9d2ee975ef9f; paramiko 3.4.0; russh 0.40.2), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • Go golang.org/x/crypto

    Affected
    >= 0.1.0, < 0.17.0< 0.0.0-20231218163308-9d2ee975ef9f
    Fixed in
    0.17.0, 0.0.0-20231218163308-9d2ee975ef9f

  • PyPI paramiko

    Affected
    >= 2.5.0, < 3.4.0
    Fixed in
    3.4.0

  • crates.io russh

    Affected
    < 0.40.2
    Fixed in
    0.40.2

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
5.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS
  • CVE-2023-48795: 93.55% estimated exploitation activity in the next 30 days; percentile 99.84 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary Terrapin is a prefix truncation attack targeting the SSH protocol. More precisely, Terrapin breaks the integrity of SSH's secure channel. By carefully adjusting the sequence numbers during the handshake, an attacker can remove an arbitrary amount of messages sent by the client or server at the beginning of the secure channel without the client or server noticing it. Mitigations To mitigate this protocol vulnerability, OpenSSH suggested a so-called "strict kex" which alters the SSH handshake to ensure a Man-in-the-Middle attacker cannot introduce unauthenticated messages as well as convey sequence number manipulation across handshakes. Warning: To take effect, both the client and server must support this countermeasure. As a stop-gap measure, peers may also (temporarily) disable the affected algorithms and use unaffected alternatives like AES-GCM instead until patches are available. Details The SSH specifications of ChaCha20-Poly1305 (chacha20-poly1305@openssh.com) and…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-45x7-px36-x8w8

  2. Revision 1 · created ·

    Published from osv record GHSA-45x7-px36-x8w8

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2023-48795

Advisory: Prefix Truncation Attack against ChaCha20-Poly1305 and Encrypt-then-MAC aka Terrapin
IDs: CVE-2023-48795, GHSA-45x7-px36-x8w8
Record: https://patchnext.com/advisories/cve-2023-48795 (revision 2, source checked 26 Oct 2026, 13:41 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: golang.org/x/crypto 0.17.0, 0.0.0-20231218163308-9d2ee975ef9f; paramiko 3.4.0; russh 0.40.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go golang.org/x/crypto: affected >= 0.1.0, < 0.17.0; < 0.0.0-20231218163308-9d2ee975ef9f; fixed in 0.17.0, 0.0.0-20231218163308-9d2ee975ef9f
- PyPI paramiko: affected >= 2.5.0, < 3.4.0; fixed in 3.4.0
- crates.io russh: affected < 0.40.2; fixed in 0.40.2

## Suggested inspection (read-only)
- Go golang.org/x/crypto: check the installed version with your package manager.
- `python -m pip show paramiko`: prints the installed version. Run with the environment that serves production active.
- crates.io russh: 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 golang.org/x/crypto, paramiko, russh.
- 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://osv.dev/vulnerability/GHSA-45x7-px36-x8w8 (OSV record GHSA-45x7-px36-x8w8 lists affected ranges: crates.io russh >=0 =0.1.0 =0 =2.5.0 <3.4.0 (fixed))
- Verified: https://github.com/advisories/GHSA-45x7-px36-x8w8 (GitHub-reviewed advisory GHSA-45x7-px36-x8w8 lists affected ranges: crates.io russh >=0 =2.5.0 =0.1.0 =0 <0.0.0-20231218163308-9d2ee975ef9f)

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