neqo-qpack has iInteger overflow in qpack dynamic table indexing

published 2026-03-04 8mo ago modified 2026-03-04 8mo ago

cvss: —; not scored
cisa kev: Not listed; not in CISA's catalog
epss: —; no score, EPSS covers CVEs only
public exploits: 0; none known

### 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.

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Affected packages

ecosystem	package	affected	fixed in
crates.io	neqo-qpack	<=0.22.2	no fix listed

Classification

Weakness

CWE-190 Integer Overflow or Wraparound

References

Sources

GitHub Advisory GHSA-6w86-wgwq-rgq8

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