CVE-2026-119237

Published Nov 11, 2026 Modified Nov 11, 2026

Description

In proxygen's HTTP/3 session, when a HEADERS block referenced QPACK dynamic table entries that had not yet been received, header decoding for that stream was paused, but the session continued to read the stream from the QUIC transport. The unread data bypassed the session's ingress buffer limit, returned flow-control credit to the peer, and was re-scanned in full on every read. With QPACK blocked streams enabled (the default), a remote, unauthenticated HTTP/3 peer could send a HEADERS block that references a dynamic table insert it never sends, followed by a continuous stream of data, causing memory growth until the request timed out and CPU usage that grows quadratically, leading to denial of service. This issue affects proxygen versions prior to v2026.11.09.00.

Is your site exposed to CVE-2026-119237?

Run a free security scan — no signup, results in seconds.

References

Frequently Asked Questions

What is CVE-2026-119237? +
In proxygen's HTTP/3 session, when a HEADERS block referenced QPACK dynamic table entries that had not yet been received, header decoding for that stream was paused, but the session continued to read the stream from the QUIC transport. The unread data bypassed the session's ingress buffer limit, returned flow-control credit to the peer, and was re-scanned in full on every read. With QPACK blocked streams enabled (the default), a remote, unauthenticated HTTP/3 peer could send a HEADERS block that references a dynamic table insert it never sends, followed by a continuous stream of data, causing memory growth until the request timed out and CPU usage that grows quadratically, leading to denial of service. This issue affects proxygen versions prior to v2026.11.09.00.
How do I check if I'm vulnerable to CVE-2026-119237? +
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.

Don't wait for an exploit

Scan your website for vulnerabilities like CVE-2026-119237 — free, no signup required.

Patch and protect

Block known exploits with a web application firewall while you patch, or test the fix on a fresh server.

Compare VPS prices →
Sucuri Sucuri → Website firewall, malware cleanup & monitoring NordPass NordPass → Password manager with breach alerts Contabo Contabo → Cheap VPS & dedicated servers, EU/US/Asia Vultr Vultr → Cloud VPS in 30+ locations, hourly billing
NordVPN NordVPN → Hide your IP, servers in 120+ countries Surfshark Surfshark → Unlimited devices, from ~$2/mo

Affiliate links: we may earn a commission, your price stays the same.