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VulnerabilityPublished

CVE-2026-31814: libp2p rust-yamux · Integer Overflow or Wraparound

Affects libp2p rust-yamuxSource CVE Database V5

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Not known to be exploited · CVSS 8.7 High : upgrade to 0.13.9 soon.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 4.0 base score
8.7High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 40% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 0.13.9
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade rust-yamux and github/libp2p/rust-yamux to 0.13.9.

Affected software

ProductAffectedFixed in
libp2prust-yamuxAffected
  • >=0.13.0 <0.13.9
Fixed in
  • 0.13.9
crates.iogithub/libp2p/rust-yamuxpkg:cargo/github/libp2p/rust-yamuxOther threatsAffected
  • <0.13.9 >=0.13.0
Fixed in
  • 0.13.9

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

The primary mitigation is to upgrade rust-yamux to version 0.13.9 or later, where the integer overflow flaw is fixed. Organizations should audit their dependency trees to identify usage of libp2p components that include rust-yamux and ensure all instances are updated. For environments where immediate upgrade is not feasible, network-level controls such as filtering or rate limiting suspicious WindowUpdate frames may reduce exposure, though this is a partial and less reliable mitigation. Monitoring network traffic for anomalous WindowUpdate messages and implementing connection-level anomaly detection can help identify exploitation attempts. Additionally, incorporating robust error handling and connection restart mechanisms in applications using rust-yamux can minimize service disruption. Vendors and developers should also consider fuzz testing and static analysis on protocol parsers to proactively detect similar integer overflow issues in the future.

Description

Yamux is a stream multiplexer over reliable, ordered connections such as TCP/IP. From 0.13.0 to before 0.13.9, a specially crafted WindowUpdate can cause arithmetic overflow in send-window accounting, which triggers a panic in the connection state machine. This is remotely reachable over a normal network connection and does not require authentication. This vulnerability is fixed in 0.13.9.

References

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