CVE-2026-16365: mozilla firefox Improper Privilege Management
CVSS: 8.8v3.1HighModified
AliasesUBUNTU-CVE-2026-16365DEBIAN-CVE-2026-16365CGA-ccjm-xp2f-545gCGA-fqxp-7jjm-rcx2CGA-gx64-fg8g-9wc8CGA-wmwg-m38p-xwmm
Published 21-07-2026Last modified 01-09-2026
Vulnerability summary
CVE-2026-16365 is a high (CVSS 8.8) Improper Privilege Management vulnerability in mozilla firefox. EPSS estimates a 0.28% chance of exploitation in the next 30 days, higher than 18.9% of scored vulnerabilities.
CVSS score
8.8/10
010
High · v3.1 (CVE.org)EPSS score
0.28%
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 32 · Related 10MGASA-2026-0387MGASA-2026-0388OPENSUSE-SU-2026:11358-1OPENSUSE-SU-2026:11373-1OPENSUSE-SU-2026:11678-1OPENSUSE-SU-2026:21713-1RHSA-2026:67129RHSA-2026:67133RHSA-2026:68549RHSA-2026:70642RHSA-2026:73130RHSA-2026:73971RHSA-2026:76740RHSA-2026:76741RHSA-2026:76742RHSA-2026:76745RHSA-2026:76746RHSA-2026:76894RHSA-2026:76895RHSA-2026:77610RHSA-2026:77627RHSA-2026:77631RHSA-2026:77632RHSA-2026:80503RHSA-2026:81912RHSA-2026:81913RHSA-2026:82122SUSE-SU-2026:23411-1SUSE-SU-2026:23590-1SUSE-SU-2026:4140-1SUSE-SU-2026:4156-1SUSE-SU-2026:4268-1CGA-3WH5-W9QX-RP3J
Timeline
- 21-07-2026PublishedVulnerability first disclosed.
- 01-09-2026Last modifiedVulnerability information updated.
Description
Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 153, Thunderbird 153, Firefox ESR 140.15, and Thunderbird 140.15.
CVSS metrics
4 scores · 4 sources · 1 versionHigh 8.8Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HSourcesAll 4 agree
- OSV · UbuntuEcosystem advisory · calculated8.8HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated8.8HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- NVDNIST8.8HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.28%
Chance of exploitation in the next 30 days
Percentile
19%
Versus all other CVEs
30-day change
0.00 pp
From 0.28% on 19-09-2026
19-09-202619-10-2026
EPSS score0.28%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-269Improper Privilege ManagementThe product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.
- CWE-284Improper Access ControlThe product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
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
Debian2 products
- firefox-esr< 140.15.0esr-1~deb12u1 | < 140.15.0esr-1~deb13u1 | < 140.15.0esr-1
- thunderbird< 1:140.15.0esr-1~deb12u1 | < 1:140.15.0esr-1~deb13u1 | < 1:153.2.0esr-1
Mozilla2 products
- firefox< 153.0.0
- thunderbird< 153.0
Wolfi2 products
- firefox< 153.0-r0
- firefox-docker-selenium-compat< 153.0-r0
5 vendors · 16 products
References
9 links- bugzilla.mozilla.org/show_bug.cgi?id=2049149Permissions Required
- www.mozilla.org/security/advisories/mfsa2026-68/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-71/Vendor Advisory
