CVE-2026-8956

⛔ critical

Summary

Integer overflow in the Networking: JAR component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

CVSS Score

9.8

Critical

EPSS Score

0.1

Exploit Probability

Published Date

2026-05-19

First Seen: 2026-05-20

📊 Relative Risk Intelligence

This CVE is Very High Risk - more severe than 90.5% of all 338,292 vulnerabilities in our database.

#31,990

Top 10% most severe

Severity Percentile

🎯 CISA SSVC Assessment Updated: May 19, 2026

🔍 Exploitation Status

None

No known exploits

⚙️ Automatable

YES

Can be exploited automatically

💥 Technical Impact

Total

Complete system compromise possible

🏆 Discovered By

Yaqoub Aldurayhim

SSVC data provided by CISA

Last Modified 2026-05-20

Source NVD 🔗

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

CWE IDs (Weakness Types)

CWE-190

📦 Affected Products 4

Vendor	Product	Status	Affected Versions
mozilla	firefox	Affected	< 140.11.0
mozilla	firefox	Affected	< 151.0.0
mozilla	thunderbird	Affected	< 140.11
mozilla	thunderbird	Affected	< 151.0.0

🔗 References 5

https://bugzilla.mozilla.org/show_bug.cgi?id=2032427

Permissions Required

https://www.mozilla.org/security/advisories/mfsa2026...

Vendor Advisory

https://www.mozilla.org/security/advisories/mfsa2026...

Vendor Advisory

https://www.mozilla.org/security/advisories/mfsa2026...

Vendor Advisory

https://www.mozilla.org/security/advisories/mfsa2026...

Vendor Advisory

🔗 Related CVEs 6

CVE ID	Severity	CVSS	EPSS	Summary	Published
CVE-2026-16349	⛔ critical	9.8	0.2	Same-origin policy bypass in the DOM: Navigation component. This vulnerability was fixed in Firefox 153, Firefox ESR 115...	2026-07-21
CVE-2026-16350	⛔ critical	9.8	0.4	Incorrect boundary conditions in the Audio/Video: cubeb component. This vulnerability was fixed in Firefox 153, Firefox ...	2026-07-21
CVE-2026-16351	⛔ critical	9.8	0.4	Sandbox escape due to use-after-free in the DOM: Navigation component. This vulnerability was fixed in Firefox 153, Fire...	2026-07-21
CVE-2026-16352	⛔ critical	9.8	0.4	Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox 15...	2026-07-21
CVE-2026-16353	⛔ critical	9.8	0.4	Invalid pointer in the DOM: Bindings (WebIDL) component. This vulnerability was fixed in Firefox 153, Firefox ESR 115.38...	2026-07-21
CVE-2026-16354	⚠️ high	7.5	0.3	Information disclosure in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 153, Firefox ESR 115...	2026-07-21

These CVEs affect the same products