CVE-2026-116774 russh: peer-declared zero maximum packet size permanently stalls channel writes (silent AsyncWrite hang)
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-116774?
CVE-2026-116774 is a medium-severity vulnerability in Eugeny russh, published on 27 Oct 2026.
Official description
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.
Which versions are affected by CVE-2026-116774?
How do I fix CVE-2026-116774?
No fix has been published for CVE-2026-116774 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-116774 being exploited?
There is no known exploitation of CVE-2026-116774 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-116774, GHSA-fw5c-8223-6h42, UBUNTU-CVE-2026-116774.