An open API service providing security vulnerability metadata for many open source software ecosystems.

Security Advisories: GSA_kwCzR0hTQS01cDh2LTU4cW0tYzdmcM4AAu9_

python-jwt vulnerable to token forgery with new claims


An attacker who obtains a JWT can arbitrarily forge its contents without knowing the secret key. Depending on the application, this may for example enable the attacker to spoof other user's identities, hijack their sessions, or bypass authentication.


Users should upgrade to version 3.3.4
Fixed by:




Found by Tom Tervoort

More information

The vulnerability allows an attacker, who possesses a single valid JWT, to create a new token with forged claims that the verify_jwt function will accept as valid.

The issue is caused by an inconsistency between the JWT parsers used by python-jwt and its dependency jwcrypto. By mixing compact and JSON representations, an attacker can trick jwcrypto of parsing different claims than those over which a signature is validated by jwcrypto.

Testing the fix has been added as an automated unit test to python-jwt.

If you have any questions or comments about this advisory, please open an issue in python-jwt

Source: GitHub Advisory Database
Origin: Unspecified
Severity: Critical
Classification: General
Published: almost 2 years ago
Updated: 7 days ago

CVSS Score: 9.1
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Identifiers: GHSA-5p8v-58qm-c7fp, CVE-2022-39227
References: Repository:
Blast Radius: 29.1

Affected Packages

Dependent packages: 11
Dependent repositories: 1,578
Downloads: 194,429 last month
Affected Version Ranges: < 3.3.4
Fixed in: 3.3.4
All affected versions: 0.1.0, 0.2.0, 0.2.1, 0.3.0, 0.3.1, 0.3.2, 0.3.3, 0.3.4, 0.3.5, 0.3.6, 0.3.7, 0.3.8, 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.1.0, 1.1.1, 1.1.2, 1.1.3, 1.1.5, 1.1.6, 1.1.7, 1.2.0, 1.2.1, 2.0.0, 2.0.1, 2.0.2, 3.0.0, 3.1.0, 3.2.0, 3.2.1, 3.2.2, 3.2.3, 3.2.4, 3.2.5, 3.2.6, 3.3.0, 3.3.1, 3.3.2, 3.3.3
All unaffected versions: 3.3.4, 3.3.5, 4.0.0, 4.1.0