CVE-2026-16405: mozilla firefox
CVSS: 7.5v3.1HighModified
AliasesUBUNTU-CVE-2026-16405DEBIAN-CVE-2026-16405CGA-38h6-4xc5-xxq2CGA-mm38-2c85-v584CGA-p9x7-ff63-7xwhCGA-wgm3-jg95-mjphCGA-548r-pmh6-w4rqCGA-6m68-mww3-5fv4CGA-fr76-q3r8-5v8jCGA-j8wv-xppr-jgfc
Published 21-07-2026Last modified 22-07-2026
Vulnerability summary
CVE-2026-16405 is a high (CVSS 7.5) vulnerability in mozilla firefox. EPSS estimates a 0.26% chance of exploitation in the next 30 days, higher than 16.1% of scored vulnerabilities.
CVSS score
7.5/10
010
High · v3.1 (CVE.org)EPSS score
0.26%
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 38 · Related 16MGASA-2026-0325MGASA-2026-0326OPENSUSE-SU-2026:11329-1OPENSUSE-SU-2026:11358-1OPENSUSE-SU-2026:11359-1OPENSUSE-SU-2026:21519-1OPENSUSE-SU-2026:21713-1RHSA-2026:47101RHSA-2026:47104RHSA-2026:47105RHSA-2026:49621RHSA-2026:49921RHSA-2026:49922RHSA-2026:53444RHSA-2026:53445RHSA-2026:53446RHSA-2026:53453RHSA-2026:53454RHSA-2026:53455RHSA-2026:53475RHSA-2026:54180RHSA-2026:54181RHSA-2026:54182RHSA-2026:54185RHSA-2026:54248RHSA-2026:54249RHSA-2026:54259RHSA-2026:54339SUSE-SU-2026:23115-1SUSE-SU-2026:23137-1SUSE-SU-2026:23411-1SUSE-SU-2026:23590-1SUSE-SU-2026:3200-1SUSE-SU-2026:3221-1SUSE-SU-2026:3546-1SUSE-SU-2026:4140-1SUSE-SU-2026:4156-1SUSE-SU-2026:4268-1CGA-8692-8QPQ-MMCM
Timeline
- 21-07-2026PublishedVulnerability first disclosed.
- 22-07-2026Last modifiedVulnerability information updated.
Description
Information disclosure in the Networking: WebSockets component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.
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:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- 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
0.26%
Chance of exploitation in the next 30 days
Percentile
16%
Versus all other CVEs
30-day change
0.00 pp
From 0.26% on 19-09-2026
19-09-202619-10-2026
EPSS score0.26%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected 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)
Chainguard4 products
- firefox< 153.0-r0
- firefox-docker-selenium-compat< 153.0-r0
- firefox-esr< 153.0-r1 | < 153.0-r0
- firefox-esr-140< 140.13.0-r0
Debian2 products
- firefox-esr< 140.13.0esr-1~deb12u1 | < 140.13.0esr-1~deb13u1 | < 140.13.0esr-1
- thunderbird< 1:140.13.0esr-2~deb12u1 | < 1:140.13.0esr-2~deb13u1 | < 1:140.13.0esr-1
Wolfi2 products
- firefox< 153.0-r0
- firefox-docker-selenium-compat< 153.0-r0
Mozilla1 product
- firefox< 153.0.0 | ≥ 140.1.0, < 140.13.0
5 vendors · 17 products
References
10 links- bugzilla.mozilla.org/show_bug.cgi?id=2036591Permissions Required
- www.mozilla.org/security/advisories/mfsa2026-68/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-70/Vendor Advisory
