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VulnerabilityPublished Updated

CVE-2025-1010: An attacker could have caused a use-after-free via the Custom Highlight API, leading to a potentially

Source GCVE Database

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Authoritative record:CVE-2025-1010· Critical 9.8

Not known to be exploited · CVSS 9.8 Critical · fixed in 135 : patch affected systems as a priority.

Data as of 30 Oct 2026, 01:09 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 135, 128.7, 115.20
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 4 Feb 2025

  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 29 Oct 2026.

What to do

AI-suggested

Mozilla has released official fixes for this vulnerability in Firefox 135, Thunderbird 135, Firefox ESR 115.20, and Firefox ESR 128.7. Users and administrators should update affected products to these versions or later to remediate the issue. No additional mitigation steps are required beyond applying these updates.

Description

CVE-2025-1010 is a critical use-after-free vulnerability in Mozilla Firefox and Thunderbird affecting versions prior to Firefox 135 and Firefox ESR 115.20/128.7, as well as Thunderbird versions prior to 128.7 and 135. The flaw exists in the Custom Highlight API and can lead to a potentially exploitable crash. Mozilla has released fixes in Firefox 135 and corresponding Thunderbird and ESR versions to address this and related memory safety issues.

References

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