CVE-2026-102272
PyJWT BOM Bypass
Description
PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.prepare_key in jwt/algorithms.py is affected because raw-JWK detector does not normalize accepted Unicode byte-order marks before checking for JSON. This occurs when a public JWK is prefixed with a UTF-8 BOM and used in a mixed-algorithm verification path. As a result, public JWK bypasses asymmetric-key detection and becomes the HMAC secret. Consequently, an attacker who knows the public key can forge authenticated tokens. This issue is fixed in version 2.14.0.
INFO
Published Date :
Sept. 28, 2026, 9:17 p.m.
Last Modified :
Oct. 6, 2026, 6:34 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update PyJWT to version 2.14.0 or later.
- Ensure JWK keys are properly validated.
- Avoid mixed-algorithm verification paths.
- Use strong, unique secrets for HMAC.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-102272.
| URL | Resource |
|---|---|
| https://github.com/jpadilla/pyjwt/commit/180783930de91876bc0d601f826a1f2956057291 | Patch |
| https://github.com/jpadilla/pyjwt/releases/tag/2.14.0 | Product Release Notes |
| https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947 | Exploit Mitigation Vendor Advisory |
| https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947 | Exploit Mitigation Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-102272 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-102272
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-102272 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-102272 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Oct. 06, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:pyjwt_project:pyjwt:2.13.0:*:*:*:*:*:*:* Added Reference Type GitHub, Inc.: https://github.com/jpadilla/pyjwt/commit/180783930de91876bc0d601f826a1f2956057291 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/jpadilla/pyjwt/releases/tag/2.14.0 Types: Product, Release Notes Added Reference Type GitHub, Inc.: https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947 Types: Exploit, Mitigation, Vendor Advisory Added Reference Type CISA-ADP: https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947 Types: Exploit, Mitigation, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Sep. 29, 2026
Action Type Old Value New Value Added Reference https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947 Added SSVC {'id': 'CVE-2026-102272', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-29T14:45:38.333972Z'} -
New CVE Received by [email protected]
Sep. 28, 2026
Action Type Old Value New Value Added Description PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.prepare_key in jwt/algorithms.py is affected because raw-JWK detector does not normalize accepted Unicode byte-order marks before checking for JSON. This occurs when a public JWK is prefixed with a UTF-8 BOM and used in a mixed-algorithm verification path. As a result, public JWK bypasses asymmetric-key detection and becomes the HMAC secret. Consequently, an attacker who knows the public key can forge authenticated tokens. This issue is fixed in version 2.14.0. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N Added CWE CWE-347 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/102xxx/CVE-2026-102272.json">CVE-2026-102272</a> Added Reference https://github.com/jpadilla/pyjwt/commit/180783930de91876bc0d601f826a1f2956057291 Added Reference https://github.com/jpadilla/pyjwt/releases/tag/2.14.0 Added Reference https://github.com/jpadilla/pyjwt/security/advisories/GHSA-r6x4-923q-g947