PatchTheCEVCVE-2025-10529: Same-origin policy bypass in the Layout component
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Routine
MEDIUM 6.5REMOTEUPGRADEUPGRADE
CVE-2025-10529 is a medium-severity flaw (CVSS 6.5) affecting firefox, thunderbird. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Same-origin policy bypass in the Layout component. This vulnerability was fixed in Firefox 143, Firefox ESR 140.3, Thunderbird 143, and Thunderbird 140.3.
Why this priority
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 6.5 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.3% (top 78%) |
| CISA exploited list | No |
| Weakness | CWE-942 |
| Published | 2025-09-16 |
| Last modified | 2026-10-23 |
Publisher (CNA): Mozilla Corporation · Vendor: mozilla
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
mozilla firefox UPGRADE
Affected: < 140.3.0 · < 143.0
Fixed in: 140.3.0, 143.0
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy firefox || rpm -q firefox || firefox --version
2. UPGRADE to 140.3.0 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade firefox
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade firefox
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
mozilla thunderbird UPGRADE
Affected: < 143.0
Fixed in: 143.0
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy thunderbird || rpm -q thunderbird || thunderbird --version
2. UPGRADE to 143.0 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade thunderbird
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade thunderbird
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
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