jpadilla pyjwt up to 2.12.x jwt.decode signature verification

CVSS Meta Temp Score
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CTI Interest Score
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5.7$0-$5k0.00

Summaryinfo

A vulnerability was found in jpadilla pyjwt up to 2.12.x. It has been classified as critical. This issue affects the function jwt.decode. Performing a manipulation results in signature verification. This vulnerability is reported as CVE-2026-48523. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as critical has been found in jpadilla pyjwt up to 2.12.x. This affects the function jwt.decode. The manipulation with an unknown input leads to a signature verification vulnerability. CWE is classifying the issue as CWE-347. The product does not verify, or incorrectly verifies, the cryptographic signature for data. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

PyJWT is a JSON Web Token implementation in Python. From 2.9.0 to 2.12.1, there is a verifier-side algorithm allow-list bypass when jwt.decode() or jwt.decode_complete() are called with a PyJWK key. The token header alg is checked against the caller-supplied algorithms allow-list, but signature verification is performed with the algorithm bound to the PyJWK object instead of the header algorithm. An attacker who controls a registered JWK/JWKS private key can sign with a disallowed algorithm, advertise an allowed algorithm in the JWT header, and still be accepted. The issue affects the documented PyJWKClient.get_signing_key_from_jwt(...) flow. This vulnerability is fixed in 2.13.0.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-48523 since 05/21/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details are known, but no exploit is available.

Upgrading to version 2.13.0 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.9
VulDB Meta Temp Score: 5.7

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 5.4
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Signature verification
CWE: CWE-347 / CWE-345
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: pyjwt 2.13.0

Timelineinfo

05/21/2026 CVE reserved
05/28/2026 +7 days Advisory disclosed
05/28/2026 +0 days VulDB entry created
05/28/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-jq35-7prp-9v3f
Status: Confirmed

CVE: CVE-2026-48523 (🔒)
GCVE (CVE): GCVE-0-2026-48523
GCVE (VulDB): GCVE-100-366777

Entryinfo

Created: 05/28/2026 18:45
Changes: 05/28/2026 18:45 (64)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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