CVE-2026-16363

CRITICAL

9.8

CVSS v3

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.

CWE-682 CWE-843Type Confusion

How to fix

Remediation Available

firefoxDebian

Fixed in:153.0-1CVE-2026-16363

firefoxRocky

Fixed in:0:140.13.0-1.el10_2RHSA-2026:47101

Fixed in:0:140.13.0-1.el8_10RHSA-2026:47105

Fixed in:0:140.13.0-1.el9_8RHSA-2026:47104

firefoxRed Hat / RHEL

Fixed in:0:140.13.0-1.el10_2RHSA-2026:47101

Fixed in:0:140.13.0-1.el8_10RHSA-2026:47105

Fixed in:0:140.13.0-1.el9_8RHSA-2026:47104

firefox-debuginfoRed Hat / RHEL

Fixed in:0:140.13.0-1.el10_2RHSA-2026:47101

Fixed in:0:140.13.0-1.el8_10RHSA-2026:47105

Fixed in:0:140.13.0-1.el9_8RHSA-2026:47104

firefox-debuginfoRocky

Fixed in:0:140.13.0-1.el10_2RHSA-2026:47101

Fixed in:0:140.13.0-1.el8_10RHSA-2026:47105

Fixed in:0:140.13.0-1.el9_8RHSA-2026:47104

firefox-debugsourceRocky

Fixed in:0:140.13.0-1.el10_2RHSA-2026:47101

Fixed in:0:140.13.0-1.el8_10RHSA-2026:47105

Fixed in:0:140.13.0-1.el9_8RHSA-2026:47104

firefox-debugsourceRed Hat / RHEL

Fixed in:0:140.13.0-1.el10_2RHSA-2026:47101

Fixed in:0:140.13.0-1.el8_10RHSA-2026:47105

Fixed in:0:140.13.0-1.el9_8RHSA-2026:47104

firefox-x11Rocky

Fixed in:0:140.13.0-1.el9_8RHSA-2026:47104

firefox-x11Red Hat / RHEL

Fixed in:0:140.13.0-1.el9_8RHSA-2026:47104

thunderbirdRed Hat / RHEL

Fixed in:0:140.13.0-1.el10_2RHSA-2026:49621

Fixed in:0:140.13.0-1.el8_10RHSA-2026:49922

Fixed in:0:140.13.0-1.el9_8RHSA-2026:49921

thunderbirdRocky

Fixed in:0:140.13.0-1.el10_2RHSA-2026:49621

Fixed in:0:140.13.0-1.el8_10RHSA-2026:49922

Fixed in:0:140.13.0-1.el9_8RHSA-2026:49921

thunderbird-debuginfoRocky

Fixed in:0:140.13.0-1.el10_2RHSA-2026:49621

Fixed in:0:140.13.0-1.el8_10RHSA-2026:49922

Fixed in:0:140.13.0-1.el9_8RHSA-2026:49921

thunderbird-debuginfoRed Hat / RHEL

Fixed in:0:140.13.0-1.el10_2RHSA-2026:49621

Fixed in:0:140.13.0-1.el8_10RHSA-2026:49922

Fixed in:0:140.13.0-1.el9_8RHSA-2026:49921

thunderbird-debugsourceRocky

Fixed in:0:140.13.0-1.el10_2RHSA-2026:49621

Fixed in:0:140.13.0-1.el8_10RHSA-2026:49922

Fixed in:0:140.13.0-1.el9_8RHSA-2026:49921

thunderbird-debugsourceRed Hat / RHEL

Fixed in:0:140.13.0-1.el10_2RHSA-2026:49621

Fixed in:0:140.13.0-1.el8_10RHSA-2026:49922

Fixed in:0:140.13.0-1.el9_8RHSA-2026:49921

DeveloperEditionWindows application

Affected:140.13.0Fixed in:140.13.0Mozilla

Affected:153.0.0Fixed in:153.0.0Mozilla

Mozilla Firefox (en-US)Windows application

Affected:140.13.0Fixed in:140.13.0Mozilla

Affected:153.0.0Fixed in:153.0.0Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:140.13.0Fixed in:140.13.0Mozilla

Affected:141.0 153.0Fixed in:153.0Mozilla

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

0.44%probability of exploitation in 30 days

36thpercentile

Low risk: more likely to be exploited than 36% of all known CVEs.

References

Vendor Advisory4

Other references1

bugzilla.mozilla.org

Related Vulnerabilities

Other CWE-682 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2022-30780	High	7.5	56%	-	Fix
CVE-2020-14422	Medium	5.9	13%	-	Fix
CVE-2016-7433	Medium	5.3	9.8%	-	Fix
CVE-2023-35641	High	8.8	7.2%	-	Fix
CVE-2018-8319	Critical	9.8	7.0%	-	-
CVE-2020-0022	High	8.8	6.1%	-	Fix

Common questions

How do I fix CVE-2026-16363?

Published advisories record a fix for 18 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2026-16363 being actively exploited?

Not that we know of. CVE-2026-16363 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.44% is the estimated probability that it will be exploited in the next 30 days. That is higher than 36% of all scored CVEs.

How severe is CVE-2026-16363?

CVE-2026-16363 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-16363 affect?

Published advisories record a fix for firefox (Debian), firefox (Rocky), firefox (Red Hat / RHEL), firefox-debuginfo (Red Hat / RHEL), and 14 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-24.