CVE-2026-119235

Description

proxygen's QPACK decoder enforced its size limit on a string literal in an encoder-stream instruction only after the entire literal had been received. A remote, unauthenticated HTTP/3 peer could send an insert instruction on the QPACK encoder stream that declares an arbitrarily large literal and then keep sending data, causing the decoder to buffer it without bound for the lifetime of the connection and exhaust memory, leading to denial of service. The issue occurs regardless of the advertised QPACK dynamic table capacity, including when the dynamic table is disabled. This issue affects proxygen versions prior to v2026.11.09.00.

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EPSS — Exploit Prediction

0.0018

Probability of exploitation

0.07%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://github.com/meta/proxygen/commit/daf245bba7fe1304b9491403fe56f91153299781 https://www.facebook.com/security/advisories/cve-2026-119235

Frequently Asked Questions

What is CVE-2026-119235? +

proxygen's QPACK decoder enforced its size limit on a string literal in an encoder-stream instruction only after the entire literal had been received. A remote, unauthenticated HTTP/3 peer could send an insert instruction on the QPACK encoder stream that declares an arbitrarily large literal and then keep sending data, causing the decoder to buffer it without bound for the lifetime of the connection and exhaust memory, leading to denial of service. The issue occurs regardless of the advertised QPACK dynamic table capacity, including when the dynamic table is disabled. This issue affects proxygen versions prior to v2026.11.09.00.

How do I check if I'm vulnerable to CVE-2026-119235? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.