FirefoxWeb browser · Mozilla
CVE-2025-8037
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 · uneditedSetting a nameless cookie with an equals sign in the value shadowed other cookies. Even if the nameless cookie was set over HTTP and the shadowed cookie included the `Secure` attribute. This vulnerability was fixed in Firefox 141, Firefox ESR 140.1, Thunderbird 141, and Thunderbird 140.1.
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 cookie parsing flaw in Firefox and Thunderbird allows a cookie with an empty name containing an equals sign in its value to improperly shadow other cookies, bypassing the Secure attribute and potentially allowing attackers to hijack sessions or bypass authentication.
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
< 140.1< 141.0< 140.1< 141.0CVSS 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
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
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.
-
Identify the installed Firefox versionIn Firefox, access Menu > Help > About Firefox, or type about:support in the address bar to view the installed version numberAffected if The version is earlier than 140.1 or is 140.x (between 140.1 and 141.0 exclusive)
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Identify the installed Thunderbird versionIn Thunderbird, access Menu > Help > About Thunderbird, or type about:support in the address bar to view the installed version numberAffected if The version is earlier than 140.1 or is 140.x (between 140.1 and 141.0 exclusive)
You are affected if you run any version of Firefox or Thunderbird below 140.1 or in the 140.x range before 141.0.
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 · scoped140.1141.0
Upgrade to Firefox 141, Firefox ESR 140.1, Thunderbird 141, or Thunderbird 140.1 to remediate this vulnerability.
Firefox 141 (regular) or Firefox ESR 140.1; Thunderbird 141 (regular) or Thunderbird 140.1
- Check the current version of Firefox or Thunderbird (Help > About Firefox/Thunderbird)
- If using regular Firefox release: upgrade to version 141 or later
- If using Firefox ESR: upgrade to version 140.1 or later
- If using regular Thunderbird: upgrade to version 141 or later
- If using Thunderbird ESR: upgrade to version 140.1 or later
- Restart the application after upgrade
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 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 $2,560.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-8037 — 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-2025-8037 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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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- 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
- No spam, self-promotion, credentials, or personal data