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PyJWT CVE-2026-48526

| EUVDEUVD-2026-32917 HIGH
Improper Authentication (CWE-287)
2026-05-28 GitHub_M GHSA-xgmm-8j9v-c9wx PYSEC-2026-179
Python Authentication Bypass Pyjwt
7.4
CVSS 3.1 · Vendor: GitHub_M
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Severity by source

Vendor (GitHub_M) PRIMARY
7.4 HIGH
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
SUSE
HIGH
qualitative
Red Hat
7.4 HIGH
qualitative

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

Lifecycle Timeline

2
Patch available
May 28, 2026 - 17:01 EUVD
Analysis Generated
May 28, 2026 - 15:50 vuln.today

Blast Radius

ecosystem impact
† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth
  • 40,697 pypi packages depend on pyjwt (4,610 direct, 36,482 indirect)

Ecosystem-wide dependent count for version 2.13.0.

DescriptionCVE.org

PyJWT is a JSON Web Token implementation in Python. Prior to 2.13.0, when the verifier is decoding JSON Web Tokens, while supporting both asymmetric and HMAC algorithms, the library does not validate use of JSON Web Keys in HMAC algorithm, allowing attacker to use the issuer public key as the secret key for HMAC algorithm. This vulnerability is fixed in 2.13.0.

AnalysisAI

Authentication bypass in PyJWT versions prior to 2.13.0 allows remote attackers to forge valid JSON Web Tokens by exploiting an algorithm confusion flaw where the library fails to validate that a JSON Web Key intended for asymmetric verification is not reused as an HMAC shared secret. An attacker who knows the issuer's public key (typically distributed openly via JWKS endpoints) can sign HMAC-algorithm tokens with that public key and have them accepted as legitimate. No public exploit identified at time of analysis, though the underlying algorithm-confusion class is a well-documented JWT attack pattern.

Technical ContextAI

PyJWT (cpe:2.3:a:jpadilla:pyjwt) is the most widely used Python implementation of RFC 7519 JSON Web Tokens, commonly embedded in Flask, Django, and FastAPI authentication stacks. The flaw is a classic algorithm-confusion vulnerability mapped to CWE-287 (Improper Authentication): when an application configures the verifier to accept both asymmetric algorithms (RS256/ES256, which use a public key) and symmetric algorithms (HS256/HS384/HS512, which use a shared secret), PyJWT did not reject the case where the caller-supplied key was a JWK or asymmetric public key being fed into the HMAC path. Because the public key is, by design, public, an attacker can craft an HS256 token using that key bytes as the HMAC secret, and the verifier will compute the same HMAC and accept the token as valid - bypassing the trust assumption that only the holder of the private key could have produced it.

RemediationAI

Upgrade PyJWT to vendor-released patch version 2.13.0 or later (pip install --upgrade 'pyjwt>=2.13.0') as documented in advisory GHSA-xgmm-8j9v-c9wx (https://github.com/jpadilla/pyjwt/security/advisories/GHSA-xgmm-8j9v-c9wx). As a compensating control until upgrade is possible, restrict the algorithms parameter passed to jwt.decode() to a single family - pass algorithms=['RS256'] (or whichever single asymmetric algorithm your issuer uses) rather than a list that includes both HMAC and asymmetric algorithms; the side effect is loss of algorithm agility during key rotation. Additionally, ensure verification code explicitly loads the issuer's public key as a cryptography PublicKey object rather than raw bytes/PEM strings, so it cannot silently be reinterpreted as an HMAC secret. Audit JWKS-consuming code paths and reject tokens whose alg header does not match the key type retrieved from the JWKS kid.

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Vendor StatusVendor

SUSE

Severity: High
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 12 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed
SUSE Linux Enterprise Micro 5.5 Fixed
SUSE Linux Enterprise Module for Basesystem 15 SP7 Fixed

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CVE-2026-48526 vulnerability details – vuln.today
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