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CVE-2026-84120

🔶 medium
🔍 Scan for this CVE
Summary

Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

CVSS Score
5.4
Medium
EPSS Score
0.2
Exploit Probability
Published Date
2026-09-01
First Seen: 2026-09-03
📊 Relative Risk Intelligence

This CVE is Lower Risk - more severe than 22.2% of all 360,548 vulnerabilities in our database.

#280,402
Below average severity
Severity Percentile
🎯 CISA SSVC Assessment Updated: Sep 1, 2026
🔍 Exploitation Status
None
No known exploits
⚙️ Automatable
NO
Requires human interaction
💥 Technical Impact
Partial
Limited system impact
🏆 Discovered By
Ukyo Akai
SSVC data provided by CISA
Last Modified 2026-09-02
Source NVD 🔗
CVSS Vector 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
CWE IDs (Weakness Types)
CWE-416

📦 Affected Products 7

Vendor Product Status Affected Versions
mozilla firefox Affected
< 115.40.0
mozilla firefox Affected
> 116.0 < 140.15.0
mozilla firefox Affected
> 141.0.0 < 153.2.0
mozilla firefox Affected
> 154.0.0 < 155.0.0
mozilla thunderbird Affected
< 140.15.0
mozilla thunderbird Affected
> 141.0 < 153.2.0
mozilla thunderbird Affected
> 154.0 < 155.0

🔗 References 8

https://bugzilla.mozilla.org/show_bug.cgi?id=2058911
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
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-2026-84118 🔶 medium 5.4 0.2 Use-after-free in the JavaScript: GC component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderb... 2026-09-01
CVE-2026-84119 ⛔ critical 9.6 0.3 Sandbox escape due to use-after-free in the DOM: Navigation component. This vulnerability was fixed in Firefox 155, Fire... 2026-09-01
CVE-2026-84121 ⛔ critical 9.6 0.3 Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in Firefox 155, Firefo... 2026-09-01
CVE-2026-84122 🔶 medium 5.4 0.2 Use-after-free in the Audio/Video component. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, Firefox ES... 2026-09-01
CVE-2026-84123 ⚠️ high 8.8 0.2 Privilege escalation due to use-after-free in the Graphics: WebGPU component. This vulnerability was fixed in Firefox 15... 2026-09-01
CVE-2026-84124 🔶 medium 5.4 0.2 Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, Firef... 2026-09-01
These CVEs affect the same products