Vulnerability · Published Oct 27, 2026 · Assigned by mozilla
CVE-2026-117933Frame poisoning in the CSS Parsing and Computation component
Medium 5.4
In plain English
A medium-severity uncontrolled resource consumption 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 0.3% (higher than 19% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)5.4Medium
Exploit odds (30 days)0.3%top 81.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Frame poisoning in the CSS Parsing and Computation component. This vulnerability was fixed in Firefox 159, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | firefox-esr | 153.6.0esr-1~deb12u2 | DEBIAN-CVE-2026-117933 |
| Debian:13 | firefox-esr | 153.6.0esr-1~deb13u1 | DEBIAN-CVE-2026-117933 |
| Debian:14 | firefox-esr | no fix listed | DEBIAN-CVE-2026-117933 |
| Debian:12 | thunderbird | 1:153.6.0esr-1~deb12u2 | DEBIAN-CVE-2026-117933 |
| Debian:13 | thunderbird | 1:153.6.0esr-1~deb13u1 | DEBIAN-CVE-2026-117933 |
| Debian:14 | thunderbird | no fix listed | DEBIAN-CVE-2026-117933 |
| Ubuntu:22.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-117933 |
| Ubuntu:24.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-117933 |
| Ubuntu:24.04:LTS | mozjs115 | no fix listed | UBUNTU-CVE-2026-117933 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2026-117933 |
| Ubuntu:22.04:LTS | mozjs91 | no fix listed | UBUNTU-CVE-2026-117933 |
| Ubuntu:22.04:LTS | thunderbird | no fix listed | UBUNTU-CVE-2026-117933 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Firefox | see references |
| Mozilla | Thunderbird | see references |
Weakness: CWE-400 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N