CVE-2023-23605: Mozilla Firefox · Out-of-bounds Write
Affects Mozilla FirefoxSource CVE Database V5
Not known to be exploited · CVSS 8.8 High : upgrade to 109 or 102.7 soon.
Data as of 26 Oct 2026, 08:30 UTC
- EPSS
- 0.7% chance of exploitation in 30 days – higher than 52% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 109, 102.7
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 2 Jun 2023
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 109 or 102.7.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mozilla Firefox | Affected
| Fixed in
|
AI-suggested
European organizations should immediately verify their Firefox and Thunderbird versions and upgrade to Firefox 109 or later, Firefox ESR 102.7 or later, and Thunderbird 102.7 or later. Since no specific patches are linked, upgrading to these versions is the most reliable mitigation. Organizations should enforce centralized update policies to ensure all endpoints are patched promptly. Additionally, implement network-level protections such as web filtering to block access to malicious sites that could trigger exploitation attempts. User awareness training should emphasize the risks of phishing and suspicious links, as user interaction is required for exploitation. Endpoint detection and response (EDR) solutions should be tuned to detect anomalous memory corruption behaviors. Regular vulnerability scanning and penetration testing can help identify unpatched systems. For high-risk environments, consider deploying application sandboxing or isolation techniques to limit the impact of potential exploitation. Monitoring Mozilla security advisories for any updates or exploit reports is also recommended.
Description
Mozilla developers and the Mozilla Fuzzing Team reported memory safety bugs present in Firefox 108 and Firefox ESR 102.6. 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 < 109, Firefox ESR < 102.7, and Thunderbird < 102.7.