CVE-2026-102268
PyJWT: Asymmetric-PEM detection bypass: whitespace/line-ending-mutated public keys skip the HS/asymmetric confusion guard
Description
PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, is_pem_format in jwt/utils.py is affected because is_pem_format does not recognize every PEM representation accepted by the cryptography loader. This occurs when an application mixes HMAC and asymmetric algorithms and supplies a mutated public-key PEM as raw key bytes. As a result, HMACAlgorithm.prepare_key treats the unrecognized asymmetric public key as an HMAC secret. Consequently, an attacker who knows the public key can forge authenticated HMAC tokens. This issue is fixed in version 2.14.0.
INFO
Published Date :
Sept. 28, 2026, 9:17 p.m.
Last Modified :
Sept. 28, 2026, 9:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | [email protected] |
Solution
- Update PyJWT to 2.14.0 or newer.
- Ensure proper key format validation.
- Review key management practices.
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-2026-102268.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-102268 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-2026-102268
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).
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The following list is the news that have been mention
CVE-2026-102268 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-102268 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.
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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. Prior to 2.14.0, is_pem_format in jwt/utils.py is affected because is_pem_format does not recognize every PEM representation accepted by the cryptography loader. This occurs when an application mixes HMAC and asymmetric algorithms and supplies a mutated public-key PEM as raw key bytes. As a result, HMACAlgorithm.prepare_key treats the unrecognized asymmetric public key as an HMAC secret. Consequently, an attacker who knows the public key can forge authenticated HMAC tokens. This issue is fixed in version 2.14.0. Added CVSS V3.1 AV:N/AC:L/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-2026-102268.json">CVE-2026-102268</a> Added Reference https://github.com/jpadilla/pyjwt/commit/8b4e233a22206b34ec1186e912e75c0b2396ac07 Added Reference https://github.com/jpadilla/pyjwt/releases/tag/2.14.0 Added Reference https://github.com/jpadilla/pyjwt/security/advisories/GHSA-ffc3-869f-jxw9