CVE-2026-28802
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 · uneditedAuthlib is a Python library which builds OAuth and OpenID Connect servers. From version 1.6.5 to before version 1.6.7, previous tests involving passing a malicious JWT containing alg: none and an empty signature was passing the signature verification step without any changes to the application code when a failure was expected.. This issue has been patched in version 1.6.7.
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 confidenceThe Authlib Python library versions 1.6.5 through 1.6.6 contain a JWT signature verification bypass vulnerability. Attackers can craft malicious JWTs with 'alg: none' in the header and an empty signature, which the library incorrectly accepts as valid instead of rejecting the malformed token.
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>= 1.6.5, < 1.6.7CVSS 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
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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 Authlib installationRun `pip show authlib` or check your project's requirements.txt/dependencies list for the authlib packageAffected if authlib is present in your environment
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Determine installed Authlib versionRun `pip show authlib` and look for the Version field, or run `pip list | grep authlib`Affected if the version is 1.6.5, 1.6.6, or falls within the range >=1.6.5 and <1.6.7
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Locate JWT verification codeSearch your codebase for usages of `Authlib` JWT handling, such as `JwtBearer` from `authlib.integrations` or direct `jwt` module usage with Authlib's registryAffected if your code performs JWT token verification using Authlib's JWT capabilities
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Test if alg:none tokens bypass validationCreate a test JWT with header `{"alg": "none", "typ": "JWT"}`, an empty payload claim set, and an empty signature string. Attempt to verify it using your actual verification code or Authlib's jwt.decode() with the same key/config you use in productionAffected if the token is accepted as valid when it should be rejected, indicating the bypass exists
You are affected if Authlib version 1.6.5 through 1.6.6 is installed and your application performs JWT verification using this library, as it will accept tokens with alg:none and empty signatures.
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 · scoped1.6.7
Update Authlib to version 1.6.7 or later to patch the vulnerability. Review existing JWT authentication flows to ensure no tokens with alg: none are currently accepted.
Authlib version 1.6.7
- Verify current Authlib version: pip show authlib
- Upgrade Authlib to version 1.6.7 or later: pip install authlib==1.6.7
- If using a package manager like poetry or pipenv, update accordingly: poetry add authlib==1.6.7 or pipenv install authlib==1.6.7
- Verify the upgrade was successful: pip show authlib
- Run existing tests to confirm JWT signature verification now correctly rejects alg:none tokens
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-28802 — 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-2026-28802 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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- Version or environment caveats, and links to real fixes
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