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CVE-2024-9401VulnerabilityPublished Updated

CVE-2024-9401: Memory safety bugs fixed in Firefox 131, Firefox ESR 115.16, Firefox ESR 128.3, Thunderbird 131, and Thunderbird 128.3

Affects Mozilla FirefoxSource CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical · fixed in 131 : patch Mozilla Firefox as a priority.

Data as of 26 Oct 2026, 08:30 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.7% chance of exploitation in 30 days – higher than 54% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 131, 128.3, 115.16
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 Oct 2024

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: 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 26 Oct 2026.

What to do

Upgrade Mozilla Firefox to 131, 128.3 or 115.16.

Affected software

ProductAffectedFixed in
Mozilla FirefoxAffected
  • <131
  • <128.3
  • <115.16
Fixed in
  • 131
  • 128.3
  • 115.16

AI-suggested

European organizations should immediately verify the versions of Firefox and Thunderbird deployed across their environments and prioritize upgrading to Firefox 131, Firefox ESR 115.16 or 128.3, and Thunderbird 131 or 128.3 as applicable. Network-level protections such as web filtering and email scanning should be enhanced to detect and block malicious payloads targeting this vulnerability. Employing endpoint detection and response (EDR) solutions can help identify exploitation attempts or anomalous behavior related to memory corruption exploits. Organizations should also enforce strict application whitelisting and sandboxing to limit the impact of potential code execution. Regular vulnerability scanning and asset inventory updates will ensure no outdated versions remain in use. Security awareness training should emphasize the importance of applying software updates promptly. Finally, monitoring Mozilla’s official security advisories for any emerging exploit information or patches is critical for ongoing defense.

Description

Memory safety bugs present in Firefox 130, Firefox ESR 115.15, Firefox ESR 128.2, and Thunderbird 128.2. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 131, Firefox ESR < 128.3, Firefox ESR < 115.16, Thunderbird < 128.3, and Thunderbird < 131.

References

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