Distribution advisory
This page covers CVE-2025-1020 as tracked by Ubuntu, for the package firefox. The fix is available in version 135.0+build2-0ubuntu0.20.04.1; 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 high, integrity high, 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:H/I:H/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: High — total loss, or loss the attacker controls.
- Integrity impact: High — total loss, or loss the attacker controls.
- Availability impact: High — total loss, or loss the attacker controls.
Weakness class
UBUNTU-CVE-2025-1020 is classified as CWE-787: Out-of-bounds Write. Data is written past the end or before the start of a buffer, corrupting whatever is stored there.
Affected software
UBUNTU-CVE-2025-1020 is recorded against 9 packages.
- firefox (fixed in 135.0+build2-0ubuntu0.20.04.1)
- mozjs102
- mozjs115
- mozjs38
- mozjs52
- mozjs68
- mozjs78
- mozjs91
- thunderbird (fixed in 1:140.7.1+build1-0ubuntu0.22.04.1)
Timeline and source
Published on 4 February 2025 and last revised on 29 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.
References
ubuntu.com (Report)
www.cve.org (Report)
www.mozilla.org (Report)
bugzilla.mozilla.org (Report)
www.mozilla.org (Report)
www.mozilla.org (Report)
ubuntu.com (Advisory)
ubuntu.com (Advisory)
Other advisories for this package
firefox 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-787: Out-of-bounds Write) in other software:
