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CVE

CVE-2026-34950

fast-jwt has an incomplete fix for CVE-2023-48223: JWT Algorithm Confusion via Whitespace-Prefixed RSA Public Key
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CVE

CVE-2026-34950

fast-jwt has an incomplete fix for CVE-2023-48223: JWT Algorithm Confusion via Whitespace-Prefixed RSA Public Key

fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.1.0 and earlier, the publicKeyPemMatcher regex in fast-jwt/src/crypto.js uses a ^ anchor that is defeated by any leading whitespace in the key string, re-enabling the exact same JWT algorithm confusion attack that CVE-2023-48223 patched.

Package Versions Affected

Package Version
patch Availability
No items found.

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CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
9.1
-
3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
C
H
U
0
-
3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
C
H
U
-

Related Resources

No items found.

References

https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34950.json, https://github.com/nearform/fast-jwt/security/advisories/GHSA-mvf2-f6gm-w987, https://nvd.nist.gov/vuln/detail/CVE-2026-34950

Severity

9.1

CVSS Score
0
10

Basic Information

Base CVSS
9.1
EPSS Probability
0.00235%
EPSS Percentile
0.14517%
Introduced Version
0
Fix Available
e07b1fd23f02a47f1be677a21a4f07607b478e66

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