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[USN-8916-2] PyJWT vulnerabilities

Posted on 19 October 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8916-2
October 15, 2026

pyjwt vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:


Summary:

Several security issues were fixed in PyJWT.

Software Description:

Details:

USN-8916-1 fixed vulnerabilities in PyJWT. This update provides the
corresponding fix for PyJWT on Ubuntu 26.10.

Original advisory details:

YuSung Han discovered that PyJWT did not properly validate certain JWK keys
when performing HMAC verification. An attacker could possibly use this
issue to forge authentication tokens. (CVE-2026-102266)

Rohan Das discovered that PyJWT incorrectly handled redirects when fetching
key sets. A remote attacker could possibly use this issue to cause PyJWT
to disclose sensitive information. (CVE-2026-102267)

It was discovered that PyJWT incorrectly recognized certain PEM
representations. An attacker who knew the public key could possibly use
this issue to forge authentication tokens. (CVE-2026-102268)

Nuno Lopes discovered that PyJWT incorrectly handled DER public keys when
performing HMAC verification. An attacker who knew the public key could
possibly use this issue to forge authentication tokens. (CVE-2026-102271)

It was discovered that PyJWT did not properly handle certain JWK keys
prefixed with a byte-order mark. An attacker who knew the public key could
possibly use this issue to forge authentication tokens. (CVE-2026-102272)

Charles Vosburgh discovered that PyJWT incorrectly handled certain JWK
containers when performing HMAC verification. An attacker who knew the
public key could possibly use this issue to forge authentication tokens.
(CVE-2026-102273)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-8916-2
https://ubuntu.com/security/notices/USN-8916-1
CVE-2026-102266, CVE-2026-102267, CVE-2026-102268, CVE-2026-102271,
CVE-2026-102272, CVE-2026-102273

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