CVE-2026-16363: mozilla firefox Incorrect Calculation
CVSS: 9.8v3.1CriticalAnalyzed
AliasesUBUNTU-CVE-2026-16363DEBIAN-CVE-2026-16363CGA-3p45-j49h-qwx9CGA-5g8f-hjr2-qq7cCGA-mx82-w268-gvj6CGA-xcg3-596f-35r4CGA-6ggm-3hpr-222gCGA-8pxp-65hf-8jhgCGA-qhqf-7grx-5fqjCGA-w9r6-47vx-3rc5
Published 21-07-2026Last modified 22-07-2026
Vulnerability summary
CVE-2026-16363 is a critical (CVSS 9.8) Incorrect Calculation vulnerability in mozilla firefox. EPSS estimates a 0.44% chance of exploitation in the next 30 days, higher than 36.5% of scored vulnerabilities.
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)EPSS score
0.44%
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-9H56-2MMQ-96V5
Timeline
- 21-07-2026PublishedVulnerability first disclosed.
- 22-07-2026Last modifiedVulnerability information updated.
Description
JIT miscompilation in the JavaScript: WebAssembly 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 versionCritical 9.8Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HSourcesAll 4 agree
- OSV · UbuntuEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- NVDNIST9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.44%
Chance of exploitation in the next 30 days
Percentile
37%
Versus all other CVEs
30-day change
0.00 pp
From 0.44% on 19-09-2026
19-09-202619-10-2026
EPSS score0.44%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-682Incorrect CalculationThe product performs a calculation that generates incorrect or unintended results that are later used in security-critical decisions or resource management.
- CWE-843Access of Resource Using Incompatible Type ('Type Confusion')The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.
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)
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
Mozilla2 products
- firefox< 140.13.0 | < 153.0.0
- thunderbird< 140.13.0 | ≥ 141.0, < 153.0
Wolfi2 products
- firefox< 153.0-r0
- firefox-docker-selenium-compat< 153.0-r0
5 vendors · 18 products
References
10 links- bugzilla.mozilla.org/show_bug.cgi?id=2047689Permissions Required
- www.mozilla.org/security/advisories/mfsa2026-68/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-70/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-71/Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-72/Vendor Advisory
