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VulnerabilityPublished Updated

CVE-2023-4585: Mozilla Firefox · Out-of-bounds Write

Affects Mozilla FirefoxSource CVE Database V5

0

Not known to be exploited · CVSS 8.8 High : upgrade to 117 or 115.2 soon.

Data as of 26 Oct 2026, 11:42 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.7% chance of exploitation in 30 days – higher than 55% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 117, 115.2
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 11 Sep 2023

  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 117 or 115.2.

Affected software

ProductAffectedFixed in
Mozilla FirefoxAffected
  • <117
  • <115.2
Fixed in
  • 117
  • 115.2

AI-suggested

Organizations should immediately inventory their Firefox and Thunderbird deployments to identify affected versions. If you cannot patch yet, users should be advised to avoid untrusted websites and email attachments to minimize exposure. Deploying endpoint protection solutions capable of detecting exploitation attempts targeting memory corruption can provide additional defense. Network-level controls such as web filtering and email security gateways should be configured to block or flag suspicious content. Security teams should monitor for unusual process behavior or crashes indicative of exploitation attempts. Implementing strict update policies and educating users about the risks of interacting with unknown content will reduce the likelihood of successful attacks. Finally, organizations should stay informed through Mozilla security advisories for any updates or exploit disclosures related to this vulnerability.

Description

Memory safety bugs present in Firefox 116, Firefox ESR 115.1, and Thunderbird 115.1. 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 < 117, Firefox ESR < 115.2, and Thunderbird < 115.2.

References

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