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VulnerabilityPublished

CVE-2026-119236: An mvfst QUIC server retained CRYPTO frame data received at an encryption level (Initial or

Source GCVE Database

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Authoritative record:CVE-2026-119236· High

Not known to be exploited : upgrade to v2026.11.09.00 soon.

Data as of 11 Nov 2026, 20:03 UTC

Severity
High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none
Patch
Available – fixed in v2026.11.09.00, 2026.11.09.00

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 11 Nov 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 11 Nov 2026.

What to do

Upgrade mvfst to v2026.11.09.00; meta/mvfst to 2026.11.09.00.

Affected software

ProductAffectedFixed in
FacebookmvfstAffected
  • <2026.11.09.00
Fixed in
  • v2026.11.09.00
GitHubmeta/mvfstpkg:github/meta/mvfstOther threatsAffected
  • <2026.11.09.00
Fixed in
  • 2026.11.09.00

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

AI-suggested

Upgrade mvfst to version v2026.11.09.00 or later, where this issue is fixed. No other mitigation or workaround is indicated.

Description

An mvfst QUIC server vulnerability allows a remote unauthenticated client to cause unbounded memory growth by sending Handshake-level CRYPTO data after the TLS handshake has progressed past that encryption level. This can lead to denial of service. The issue affects mvfst versions prior to v2026.11.09.00.

References

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