pageant: Out-of-bounds read / oversized allocation in `pageant` MemoryMap::read via a malicious Pageant agent (Windows)

[ Why it matters ]Priority signals

• Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

pageant provides a [PageantStream] type that implements [AsyncRead] and [AsyncWrite] traits and can be used to talk to a running Pageant instance. Prior to pageant 0.2.3, the Windows pageant crate's pageant/src/wmmessage.rs MemoryMap::read function trusts a peer-controlled u32 response length supplied through the 8192-byte Pageant shared-memory mapping reached by AgentClient::connect_pageant. A local process that impersonates the Pageant window can make query_pageant_direct allocate up to approximately 4 GiB and copy beyond the mapped view, reliably crashing a russh client and conditionally exposing adjacent committed memory. This issue is fixed in pageant 0.2.3.

[ Fixes ]Fixes and patches

• pageant 0.2.3Fixed version · GitHub Advisories · rust package pageant: upgrade to 0.2.3 or later (affected <= 0.2.2)

[ Packages ]Affected open-source packages

• pageant rustAffected <= 0.2.2 · fixed in 0.2.3 · GHSA-g4mp-vgx3-xrvm

[ References ]References

• github.com/Eugeny/russh/commit/5d566989ebabfdebfe6b33243d31765a0812260b
• github.com/Eugeny/russh/releases/tag/v0.63.2
• github.com/Eugeny/russh/security/advisories/GHSA-g4mp-vgx3-xrvm