Distribution advisory
This page covers CVE-2026-4694 as tracked by Debian, for the package firefox-esr. The fix is available in version 140.9.0esr-1; earlier versions remain affected.
How this vulnerability can be exploited
This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.
CVSS metrics in full
The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Attack vector: Network — reachable from anywhere that can route to the service.
- Attack complexity: Low — the attack works reliably, with no preparation.
- Privileges required: None — an unauthenticated stranger can try it.
- User interaction: None — nobody has to be tricked into anything.
- Scope: Unchanged — the damage stays inside the vulnerable component.
- Confidentiality impact: None.
- Integrity impact: None.
- Availability impact: High — total loss, or loss the attacker controls.
Weakness class
DEBIAN-CVE-2026-4694 is classified as CWE-190: Integer Overflow or Wraparound. Arithmetic produces a value too large for its type and wraps around, so a later size or bounds check passes when it should not.
Affected software
DEBIAN-CVE-2026-4694 is recorded against 2 packages.
- firefox-esr (fixed in 140.9.0esr-1)
- thunderbird (fixed in 1:140.9.0esr-1)
Timeline and source
Published on 24 March 2026 and last revised on 4 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.
References
security-tracker.debian.org (Advisory)
Other advisories for this package
firefox-esr has other advisories on record. If you are patching this one, these are worth checking on the same host:
Same weakness in other software
These advisories are the same class of weakness (CWE-190: Integer Overflow or Wraparound) in other software:
