CVE-2026-100805: mozilla firefox Race Condition
CVSS: 7.5v3.1HighAnalyzed
AliasesUBUNTU-CVE-2026-100805
Published 29-09-2026Last modified 30-09-2026
Vulnerability summary
CVE-2026-100805 is a high (CVSS 7.5) Race Condition vulnerability in mozilla firefox. EPSS estimates a 0.21% chance of exploitation in the next 30 days, higher than 10.3% of scored vulnerabilities.
CVSS score
7.5/10
010
High · v3.1 (CVE.org)EPSS score
0.21%
0%100%
Low · Change unavailableKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 1 · Related 1Timeline
- 29-09-2026PublishedVulnerability first disclosed.
- 30-09-2026Last modifiedVulnerability information updated.
Description
Race condition, use-after-free in the Audio/Video component. This vulnerability was fixed in Thunderbird 157 and Firefox 157.
CVSS metrics
3 scores · 3 sources · 1 versionHigh 7.5Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:HSourcesAll 3 agree
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.21%
Chance of exploitation in the next 30 days
Percentile
10%
Versus all other CVEs
30-day change
Change unavailable
Change unavailable
30-09-202621-10-2026
EPSS score0.21%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
- CWE-416Use After FreeThe product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
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)
Mozilla2 products
- firefox< 157.0.0
- thunderbird< 157.0
2 vendors · 10 products
References
6 links- www.mozilla.org/security/advisories/mfsa2026-101/Vendor Advisory