CVE-2026-16398: mozilla firefox Origin Validation Error
CVSS: 7.5v3.1HighAnalyzed
AliasesUBUNTU-CVE-2026-16398CGA-3v96-p88r-6j3gCGA-739v-6fr7-grj5CGA-97r5-fpjv-x72xCGA-pwqx-6jfh-m264
Published 21-07-2026Last modified 21-10-2026
Vulnerability summary
CVE-2026-16398 is a high (CVSS 7.5) Origin Validation Error vulnerability in mozilla firefox. EPSS estimates a 0.15% chance of exploitation in the next 30 days, higher than 3.7% of scored vulnerabilities.
CVSS score
7.5/10
010
High · v3.1 (CVE.org)EPSS score
0.15%
0%100%
Low · 0.00 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 8 · Related 9Timeline
- 21-07-2026PublishedVulnerability first disclosed.
- 21-10-2026Last modifiedVulnerability information updated.
Description
Site isolation issue in the Graphics component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.
CVSS metrics
3 scores · 3 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 3 agree
- OSV · UbuntuEcosystem 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
0.15%
Chance of exploitation in the next 30 days
Percentile
4%
Versus all other CVEs
30-day change
0.00 pp
From 0.15% on 21-09-2026
21-09-202621-10-2026
EPSS score0.15%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-346Origin Validation ErrorThe product does not properly verify that the source of data or communication is valid.
- CWE-200Exposure of Sensitive Information to an Unauthorized ActorThe product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
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< 153.0-r0
- firefox-docker-selenium-compat< 153.0-r0
Mozilla2 products
- firefox< 153.0.0
- thunderbird< 153.0
Wolfi2 products
- firefox< 153.0-r0
- firefox-docker-selenium-compat< 153.0-r0
4 vendors · 14 products
References
6 links- bugzilla.mozilla.org/show_bug.cgi?id=2048345Permissions Required
- www.mozilla.org/security/advisories/mfsa2026-68/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-71/Vendor Advisory