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Fencer Intel
medium 4.3

CVE-2026-116774 json

russh: peer-declared zero maximum packet size permanently stalls channel writes (silent AsyncWrite hang)

published 13d ago modified 10d ago also EUVD-2026-111389 , GHSA-fw5c-8223-6h42

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 17%
public exploits
0
none known

Summary

russh is a Rust SSH client and server library that includes an SSH agent protocol implementation. From 0.60.0 until 0.65.0, channel-open parsing accepts a peer-declared maximum_packet_size of zero and passes it into ChannelTx::poll_writable in russh/src/channels/io/tx.rs. The Channel::data, Channel::make_writer, and Channel::into_stream asynchronous write paths then calculate a writable size of zero and remain pending forever because window adjustments cannot satisfy a static zero packet maximum. An authenticated client can strand server writes, and a malicious server can strand client writes, allowing affected tasks, channels, and connections to accumulate without surfacing an error. This issue is fixed in version 0.65.0.

Patch / fix

  • crates.io russh 0.65
  • warpgate_project warpgate 0.65.0
  • russh_project russh 0.65.0

Is CVE-2026-116774 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-116774 updated cvss 4.3

russh: russh: Denial of service via zero maximum packet size

  • Red Hat Hardened Images openshell 0.1.6-0.1.hum1, openshell-gateway 0.1.6-0.1.hum1, python3-openshell 0.1.6-0.1.hum1
    fixed: vendor fix RHSA-2026:93904

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
12d ago

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
GitHub 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
crates.io russh
>=0.60.0, <0.65
0.65

Affected products

  • Eugeny russh

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-835 Loop with Unreachable Exit Condition

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.