CVE-2026-8946: mozilla firefox
CVSS: 7.5v3.1HighModified
AliasesUBUNTU-CVE-2026-8946DEBIAN-CVE-2026-8946CGA-cc96-495f-j8ccCGA-fjph-2vj5-gmr6CGA-x794-92fw-6h8fCGA-x9vm-9qcv-wv4v
Published 19-05-2026Last modified 15-07-2026
Vulnerability summary
CVE-2026-8946 is a high (CVSS 7.5) vulnerability in mozilla firefox. EPSS estimates a 0.60% chance of exploitation in the next 30 days, higher than 47.8% of scored vulnerabilities.
CVSS score
7.5/10
010
High · v3.1 (CVE.org)EPSS score
0.60%
0%100%
Low · +0.04 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 27 · Related 5MGASA-2026-0164MGASA-2026-0165OPENSUSE-SU-2026:10813-1OPENSUSE-SU-2026:10863-1OPENSUSE-SU-2026:10864-1OPENSUSE-SU-2026:21168-1RHSA-2026:21378RHSA-2026:21380RHSA-2026:21381RHSA-2026:21382RHSA-2026:22325RHSA-2026:22643RHSA-2026:26174RHSA-2026:26268RHSA-2026:26269RHSA-2026:26270RHSA-2026:26491RHSA-2026:26492RHSA-2026:26493RHSA-2026:26521RHSA-2026:26536RHSA-2026:26539RHSA-2026:26551RHSA-2026:26606RHSA-2026:26629RHSA-2026:26630RHSA-2026:27715CGA-87Q7-2FX4-9JC6
Timeline
- 19-05-2026PublishedVulnerability first disclosed.
- 15-07-2026Last modifiedVulnerability information updated.
Description
Incorrect boundary conditions in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
CVSS metrics
4 scores · 4 sources · 1 versionHigh 7.5Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NSourcesAll 4 agree
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS trend
Probability
0.60%
Chance of exploitation in the next 30 days
Percentile
48%
Versus all other CVEs
30-day change
+0.04 pp
From 0.56% on 19-09-2026
19-09-202619-10-2026
EPSS score0.60%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-119Improper Restriction of Operations within the Bounds of a Memory BufferThe product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
- CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.
Affected systems
Ubuntu8 products
- mozjs102All versions (No fix recorded)
- mozjs115All versions (No fix recorded)
- mozjs38All versions (No fix recorded)
- mozjs52All versions (No fix recorded)
- mozjs68All versions (No fix recorded)
Chainguard2 products
- firefox< 151.0.1-r0
- firefox-esr< 140.11.0-r0
Debian2 products
- firefox-esr< 140.11.0esr-1~deb12u1 | < 140.11.0esr-1~deb13u1 | < 140.11.0esr-1
- thunderbird< 1:140.11.0esr-1~deb12u1 | < 1:140.11.0esr-1~deb13u1 | < 1:140.11.0esr-1
Mozilla2 products
- firefox< 115.36.0 | < 151.0.0 | ≥ 140.0, < 140.11.0
- thunderbird< 140.11
Wolfi1 product
- firefox< 151.0.1-r0
5 vendors · 15 products
