FirefoxWeb browser · Mozilla
CVE-2025-1010
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedAn attacker could have caused a use-after-free via the Custom Highlight API, leading to a potentially exploitable crash. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA use-after-free vulnerability exists in the Custom Highlight API of Firefox and Thunderbird. An attacker can trigger this memory corruption by causing the browser to access memory after it has been freed, potentially leading to a crash or arbitrary code execution.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
FirefoxWeb browser
< 115.20.0< 135.0>= 128.1.0, < 128.7.0>= 128.0.1, < 128.7.0>= 131.0, < 135.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed Mozilla productRun 'firefox --version' or 'thunderbird --version' from command line, or check Help > About in the applicationAffected if Either Firefox or Thunderbird is installed
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Check Firefox version against affected rangesIf Firefox is installed, run 'firefox --version' and compare to: < 115.20.0, OR >= 128.1.0 and < 128.7.0, OR >= 135.0 (actually < 135.0 is vulnerable)Affected if Firefox version is less than 115.20.0, OR between 128.1.0 and 128.6.x, OR less than 135.0 (all versions before 135.0 except 115.20-128.0 are affected)
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Check Thunderbird version against affected rangesIf Thunderbird is installed, run 'thunderbird --version' and compare to: >= 128.0.1 and < 128.7.0, OR >= 131.0 and < 135.0Affected if Thunderbird version is between 128.0.1 and 128.6.x, OR between 131.0 and 134.x
The environment is affected if Firefox is installed with a version less than 115.20.0, between 128.1.0-128.6.x, or less than 135.0; or if Thunderbird is installed with a version between 128.0.1-128.6.x or between 131.0-134.x.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped115.20.0128.7.0135.0
Update affected Mozilla products to the patched versions: Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, or Thunderbird 135.
Firefox 135.0 (or Firefox ESR 115.20 / ESR 128.7); Thunderbird 128.7 or 135.0
- Identify the currently installed Firefox or Thunderbird version via Help > About (or running 'firefox --version' / 'thunderbird --version')
- If using Firefox: Upgrade to version 135.0 or later for the main release, or ESR 115.20/128.7 for Extended Support Release branches
- If using Thunderbird: Upgrade to version 128.7 or later, or version 135.0 or later
- Restart the application after updating
- Verify the update was successful by checking Help > About again
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,424.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-1010 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-1010 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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