CVE-2025-45770
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 · uneditedjwt v5.4.3 was discovered to contain weak encryption. NOTE: this issue has been disputed on the basis that key lengths are expected to be set by an application, not by this library. This dispute is subject to review under CNA rules 4.1.4, 4.1.14, and other rules; the dispute tagging is not meant to recommend an outcome for this CVE Record.
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 confidenceThe jwt v5.4.3 library was found to allow weak encryption by not enforcing minimum key length requirements for HMAC-based algorithms. This could allow attackers to brute-force JWT signatures if applications using the library do not implement their own key validation.
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<= 5.4.3CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/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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Check installed jwt library versionRun 'pip show jwt' or check your requirements.txt/package-lock.json for the jwt library version. If using Node.js, run 'npm list jwt' or check package.json.Affected if The installed version is 5.4.3 or lower (any version up to and including 5.4.3).
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Identify JWT algorithm usageSearch your codebase for JWT signing/verification calls. Look for algorithm parameters set to HS256, HS384, HS512, or 'HS256' / 'HMAC' in jwt.encode(), jwt.sign(), jwt.decode(), or jwt.verify() functions.Affected if Your application uses HMAC-based algorithms (HS256, HS384, HS512) for signing or verifying JWTs.
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Inspect key/secret sourceFind where the secret key is defined or loaded for JWT operations. Check configuration files, environment variables, or code where the secret is passed to jwt.encode()/jwt.sign() or jwt.verify().Affected if A static secret or key is used directly without being validated for minimum length.
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Check for application-layer key validationSearch your codebase for any custom key validation logic before JWT operations. Look for checks that verify key length, entropy, or strength before using the key with jwt functions.Affected if No custom key validation exists in your application code - the key is passed directly to JWT functions without length or strength checks.
You are affected if you are using jwt library version 5.4.3 or lower with HMAC algorithms and your application does not implement its own key length validation before signing or verifying tokens.
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 · scopedApplications using this library should enforce strong, minimum-length keys (at least 256 bits for HMAC-SHA256) at the application layer. Consider reviewing key management practices and implementing key validation before signing tokens.
latest stable version of the jsonwebtoken library (or jwt library)
- 1. Identify the JWT library in use by checking package.json for 'jsonwebtoken' or similar JWT package dependencies
- 2. Run 'npm list jsonwebtoken' (or equivalent for your language/framework) to confirm the currently installed version
- 3. Upgrade to the latest version of the JWT library to receive key length validation improvements: run 'npm install jsonwebtoken@latest' or update the version in package.json
- 4. Verify the upgrade was successful by running 'npm list jsonwebtoken'
- 5. Test that JWT signing and verification still work correctly with your existing keys
- 6. If using HMAC algorithms, ensure your secret keys meet the minimum recommended length (256 bits / 32 bytes for HS256)
- 7. Consider implementing explicit key length validation in your application code as a defense-in-depth measure
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-45770 — 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-2025-45770 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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