CVE-2026-35536
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 · uneditedIn Tornado before 6.5.5, cookie attribute injection could occur because the domain, path, and samesite arguments to .RequestHandler.set_cookie were not checked for crafted characters.
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 · moderate confidenceIn Tornado before 6.5.5, the RequestHandler.set_cookie method fails to validate the domain, path, and samesite arguments, allowing an attacker to inject crafted characters that could manipulate cookie attributes beyond intended values.
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< 6.5.5CVSS 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
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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.
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Check Tornado version installedRun 'pip show tornado' or check your requirements lock file to find the installed version numberAffected if The installed version is lower than 6.5.5 (e.g., 6.5.4, 6.5.3, 6.4.x, etc.)
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Find set_cookie usage in codeSearch your codebase for 'set_cookie' method calls, looking for patterns like handler.set_cookie(..., domain=..., path=..., samesite=...)Affected if Your application code calls RequestHandler.set_cookie with domain, path, or samesite parameters
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Check if cookie parameters accept untrusted inputReview set_cookie calls to determine if the domain, path, or samesite arguments receive values from user requests (e.g., request.query_params, request.body, cookies) without validationAffected if User-supplied input flows into the domain, path, or samesite parameters of set_cookie without sanitization
You are affected if you are running Tornado version below 6.5.5 AND your application uses set_cookie with user-controlled domain, path, or samesite parameters.
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 · scoped6.5.5
Upgrade to Tornado version 6.5.5 or later which implements proper input validation for cookie attributes.
6.5.5
- 1. Check your current Tornado version by running: pip show tornado
- 2. Upgrade Tornado to version 6.5.5 or later using: pip install --upgrade tornado>=6.5.5
- 3. Verify the upgrade was successful by running: pip show tornado
- 4. Test your application to ensure cookie functionality works correctly after the upgrade
- 5. If using a requirements file, update the Tornado version constraint to: tornado>=6.5.5
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation3.0 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 $2,272.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-35536 — 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-2026-35536 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