Security readout for executives and security teams
Plain-English summary
This flaw can let an attacker get a forged JWT accepted when an application expects asymmetric signing but the library accepts a symmetric algorithm instead. For affected jsonwebtoken versions before 4.2.2, that can undermine login or API authorization decisions that rely on JWT verification.
Executive priority
Treat this as urgent where JWTs protect customer accounts, admin portals, or APIs. The business risk is unauthorized access if vulnerable versions remain in production, even though the provided sources do not show active exploitation.
Technical view
CVE-2015-9235 is algorithm-confusion in the jsonwebtoken Node module before 4.2.2. A token expected to be signed with an RS/ES asymmetric algorithm could instead be submitted using an HS symmetric algorithm, bypassing verification under vulnerable conditions. The CVE lists CWE-20 and no CVSS score.
Likely exposure
Exposure is likely in Node.js services using jsonwebtoken before 4.2.2 for JWT verification, especially where RS or ES algorithms are expected for authentication or authorization tokens.
Exploitation context
The source bundle includes public advisories, research writeups, and a fixing commit. It does not indicate CISA KEV listing or active exploitation, so active exploitation should not be claimed from these sources.
Researcher notes
Focus on dependency version, JWT verification call sites, algorithm allowlisting, and whether asymmetric public keys are used in contexts that could be confused with HS verification. Evidence is incomplete on real-world exploitation and CVSS severity.
Mitigation direction
- Upgrade jsonwebtoken to version 4.2.2 or later.
- Review vendor guidance and the linked fixing commit for exact remediation details.
- Ensure JWT verification only accepts expected algorithms for the configured key type.
- Rotate credentials or signing material if forged-token exposure is suspected.
- Add regression tests for rejecting algorithm mismatches.
Validation and detection
- Inventory applications and lockfiles for jsonwebtoken versions before 4.2.2.
- Identify JWT verification paths that expect RS or ES algorithms.
- Confirm accepted algorithms are explicitly constrained to the intended family.
- Review authentication and authorization logs for suspicious token acceptance patterns.
- Run controlled regression tests that verify HS tokens are rejected in RS/ES contexts.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-20: Exact CWE lookup
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Open ATT&CK lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2015-9235 mapping review
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Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://nodesecurity.io/advisories/17CVE reference · x_refsource_MISC
- https://github.com/auth0/node-jsonwebtoken/commit/1bb584bc382295eeb7ee8c4452a673a77a68b687CVE reference · x_refsource_MISC
- https://auth0.com/blog/2015/03/31/critical-vulnerabilities-in-json-web-token-libraries/CVE reference · x_refsource_MISC
- https://www.timmclean.net/2015/02/25/jwt-alg-none.htmlCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.