Vulnerability · Published Feb 24, 2026 · Assigned by mozilla
CVE-2026-2781Integer overflow in the Libraries component in NSS
High 8.8
In plain English
A high-severity integer overflow in Firefox from Mozilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 38% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)8.8High
Exploit odds (30 days)0.4%top 62.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Integer overflow in the Libraries component in NSS. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, Thunderbird 140.8, and Firefox ESR 115.35.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | firefox | 140.8.0-2.el10_1 | ALSA-2026:3361 |
| AlmaLinux:8 | firefox | 140.8.0-2.el8_10.alma.1 | ALSA-2026:3338 |
| AlmaLinux:9 | firefox | 140.8.0-2.el9_7.alma.1 | ALSA-2026:3339 |
| AlmaLinux:9 | firefox-x11 | 140.8.0-2.el9_7.alma.1 | ALSA-2026:3339 |
| AlmaLinux:10 | thunderbird | 140.8.0-2.el10_1.alma.1 | ALSA-2026:3517 |
| AlmaLinux:8 | thunderbird | 140.8.0-1.el8_10.alma.1 | ALSA-2026:3515 |
| AlmaLinux:9 | thunderbird | 140.8.0-1.el9_7.alma.1 | ALSA-2026:3516 |
| Debian:12 | firefox-esr | 140.8.0esr-1~deb12u1 | DEBIAN-CVE-2026-2781 |
| Debian:12 | firefox-esr | 140.8.0esr-1~deb12u1 | DSA-6148-1 |
| Debian:13 | firefox-esr | 140.8.0esr-1~deb13u1 | DSA-6148-1 |
| Debian:13 | firefox-esr | 140.8.0esr-1~deb13u1 | DEBIAN-CVE-2026-2781 |
| Debian:14 | firefox-esr | 140.8.0esr-1 | DEBIAN-CVE-2026-2781 |
| Debian:12 | nss | 2:3.87.1-1+deb12u2 | DEBIAN-CVE-2026-2781 |
| Debian:12 | nss | 2:3.87.1-1+deb12u2 | DSA-6149-1 |
| Debian:13 | nss | 2:3.110-1+deb13u1 | DEBIAN-CVE-2026-2781 |
| Debian:13 | nss | 2:3.110-1+deb13u1 | DSA-6149-1 |
| Debian:14 | nss | 2:3.121-1 | DEBIAN-CVE-2026-2781 |
| Debian:12 | thunderbird | 1:140.8.0esr-1~deb12u1 | DEBIAN-CVE-2026-2781 |
| Debian:12 | thunderbird | 1:140.8.0esr-1~deb12u1 | DSA-6152-1 |
| Debian:13 | thunderbird | 1:140.8.0esr-1~deb13u1 | DEBIAN-CVE-2026-2781 |
| Debian:13 | thunderbird | 1:140.8.0esr-1~deb13u1 | DSA-6152-1 |
| Debian:14 | thunderbird | 1:140.8.0esr-1 | DEBIAN-CVE-2026-2781 |
| Rocky Linux:10 | firefox | 0:140.8.0-2.el10_1 | RLSA-2026:3361 |
| Rocky Linux:8 | firefox | 0:140.8.0-2.el8_10 | RLSA-2026:3338 |
| Rocky Linux:9 | firefox | 0:140.8.0-2.el9_7 | RLSA-2026:3339 |
| Rocky Linux:10 | thunderbird | 0:140.8.0-2.el10_1 | RLSA-2026:3517 |
| Rocky Linux:8 | thunderbird | 0:140.8.0-1.el8_10 | RLSA-2026:3515 |
| Rocky Linux:9 | thunderbird | 0:140.8.0-1.el9_7 | RLSA-2026:3516 |
| Ubuntu:22.04:LTS | nss | 2:3.98-0ubuntu0.22.04.3 | UBUNTU-CVE-2026-2781 |
| Ubuntu:22.04:LTS | nss | 2:3.98-0ubuntu0.22.04.3 | USN-8071-1 |
| Ubuntu:24.04:LTS | nss | 2:3.98-1ubuntu0.1 | UBUNTU-CVE-2026-2781 |
| Ubuntu:24.04:LTS | nss | 2:3.98-1ubuntu0.1 | USN-8071-1 |
| Ubuntu:25.10 | nss | 2:3.114-1ubuntu0.1 | USN-8071-1 |
| Ubuntu:25.10 | nss | 2:3.114-1ubuntu0.1 | UBUNTU-CVE-2026-2781 |
| Ubuntu:26.04:LTS | nss | 2:3.120-1ubuntu1 | UBUNTU-CVE-2026-2781 |
| Ubuntu:22.04:LTS | thunderbird | no fix listed | UBUNTU-CVE-2026-2781 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | see references |
| Mozilla | Thunderbird | see references |
Weakness: CWE-190 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2009552
- https://www.mozilla.org/security/advisories/mfsa2026-13/
- https://www.mozilla.org/security/advisories/mfsa2026-15/
- https://www.mozilla.org/security/advisories/mfsa2026-16/
- https://www.mozilla.org/security/advisories/mfsa2026-17/
- https://www.mozilla.org/security/advisories/mfsa2026-31/
- https://lists.debian.org/debian-lts-announce/2026/03/msg00012.html