GHSA-6w86-wgwq-rgq8 neqo-qpack has iInteger overflow in qpack dynamic table indexing
A malicious remote attacker can cause a QUIC connection to fail or enter an inconsistent state via integer overflow in the neqo-qpack library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is GHSA-6w86-wgwq-rgq8?
GHSA-6w86-wgwq-rgq8 is a vulnerability in neqo-qpack, published on 4 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Summary
An unsanitized qpack index can lead to an integer overflow, panicing in debug mode, accessing the wrong or no dynamic table entry in release mode.
What does this mean for Firefox? Firefox runs Neqo in release mode. A malicious remote can cause its own QUIC connection to fail to use qpack, i.e. compression, or enter an inconsistent state. The remote can not crash Firefox, nor affect other QUIC connections.
Details
See fuzz report in https://github.com/mozilla/neqo/issues/3406.
PoC
See test in pull request.
Impact
All Firefox users. Though vulnerability likely scoped to same connection, i.e. low impact.
Which versions are affected by GHSA-6w86-wgwq-rgq8?
2 open source packages ship an affected version, including neqo-qpack.
| Package | Affected | Fixed in |
|---|---|---|
neqo-qpack crates.io | All versions to 0.22.2 | None |
neqo-qpack crates.io | All versions to 0.22.2 | None |
How do I fix GHSA-6w86-wgwq-rgq8?
No fix has been published for GHSA-6w86-wgwq-rgq8 yet. Limit exposure of the affected software until one is available.
Is GHSA-6w86-wgwq-rgq8 being exploited?
There is no known exploitation of GHSA-6w86-wgwq-rgq8 in the wild and no public exploit code.