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VulnerabilityPublished Updated

CVE-2026-100782: Mozilla Firefox · Memory Buffer Overflow

Affects Mozilla FirefoxSource CVE Database V5

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Not known to be exploited · CVSS 8.8 High.

Data as of 13 Nov 2026, 23:53 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 29 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

What to do

AI-suggested

Official fixes have been released by Mozilla in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, Firefox ESR 140.17, Thunderbird 157, Thunderbird 140.17, and Thunderbird 153.4. Users and administrators should apply these updates promptly to remediate the vulnerability. No additional mitigation steps are indicated by the vendor advisory.

Description

CVE-2026-100782 is a high-severity privilege escalation vulnerability in Mozilla Firefox and Thunderbird caused by incorrect boundary conditions in the Graphics component. The issue allows an attacker to escalate privileges due to improper handling of memory boundaries. Mozilla has fixed this vulnerability in multiple versions of Firefox and Thunderbird, including Firefox ESR 153.4, Firefox 157, and Thunderbird 157 among others.

References

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