CVE-2026-8950

⛔ critical

Summary

Same-origin policy bypass in the Networking: HTTP component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

CVSS Score

9.3

Critical

EPSS Score

0.0

Exploit Probability

Published Date

2026-05-19

First Seen: 2026-05-20

📊 Relative Risk Intelligence

This CVE is High Risk - more severe than 88.6% of all 333,415 vulnerabilities in our database.

#37,915

Top 25% most severe

Severity Percentile

🎯 CISA SSVC Assessment Updated: May 19, 2026

🔍 Exploitation Status

None

No known exploits

⚙️ Automatable

Requires human interaction

💥 Technical Impact

Partial

Limited system impact

🏆 Discovered By

Jakub Szymsza

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:R/S:C/C:H/I:H/A:N

CWE IDs (Weakness Types)

CWE-346

📦 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=1965430

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-2026-13356	🔶 medium	6.3	0.1	A malicious webpage could interrupt a pending navigation by enqueuing a synchronous JavaScript dialog, causing the brows...	2026-07-07
CVE-2026-57962	🔶 medium	5.3	0.2	A malicious LDAP server, which a Thunderbird user is configured to query for address-book autocomplete, can stash arbitr...	2026-07-01
CVE-2026-57963	🔶 medium	6.5	0.2	An attacker who can send HTML chat messages (via Matrix or XMPP) can inject arbitrary styled content, phishing links, an...	2026-07-01
CVE-2026-14241	⛔ critical	9.8	0.2	Memory safety bugs present in Firefox 152.0.3. Some of these bugs showed evidence of memory corruption and we presume th...	2026-06-30
CVE-2026-12289	⚠️ high	8.8	0.4	Privilege escalation in the Graphics: WebRender component. This vulnerability was fixed in Firefox 152, Firefox ESR 140....	2026-06-16
CVE-2026-12290	⚠️ high	8.1	0.4	Memory safety bug fixed in Firefox 152. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115...	2026-06-16

These CVEs affect the same products