What’s Vulnerable › Vulnerabilities

CVE-2026-102820: pageant: Out-of-bounds read / oversized allocation in `pageant` MemoryMap::read via a malicious Pageant agent (Windows)

• Severity: medium (CVSS 6.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-29 · updated 2026-09-30
• Weakness: CWE-125

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.

Affected products

• rust pageant: before 0.2.3
• Eugeny russh: before 0.63.2

References

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

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