PatchTheCVECVE-2025-10527: Sandbox escape due to use-after-free in the Graphics: Canvas2D component
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Routine
HIGH 7.1UPGRADEUPGRADE
CVE-2025-10527 is a high-severity flaw (CVSS 7.1) affecting firefox, thunderbird. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 143, Firefox ESR 140.3, Thunderbird 143, and Thunderbird 140.3.
Why this priority
- High severity
A fixed release or distro patch exists.
Risk facts
| CVSS score | 7.1 (High) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | Required |
| EPSS exploit chance | 0.3% (top 81%) |
| CISA exploited list | No |
| Weakness | CWE-416 |
| 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
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: < 140.3.0 · >= 141.0 and < 143.0
Fixed in: 140.3.0, 143.0
Safe to downgrade to: a release before 141.0
1. Check installed version
apt-cache policy thunderbird || rpm -q thunderbird || thunderbird --version
2. UPGRADE to 140.3.0 (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.
3. If no update is available yet, DOWNGRADE to a release before 141.0 (Debian / Ubuntu)
apt-cache madison thunderbird
sudo apt install thunderbird=<VERSION_BEFORE_141.0>
sudo apt-mark hold thunderbird
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list thunderbird
sudo dnf downgrade thunderbird-<VERSION_BEFORE_141.0>
sudo dnf versionlock add thunderbird
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
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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