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HIGH

CVE-2026-114616

Authlib accepts an empty HMAC key, allowing JWS/JWT signature forgery (HS256/HS384/HS512)

CVSS v3

7.4

HIGH

EPSS Score

—

exploit probability

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • CVE-2026-114616 Red Hat Product Security11 known affected

    authlib: authlib: Authentication bypass via zero-length HMAC key

    exploit-intelligence/vulnerability-analysis-rhel9 as a component of Exploit Intelligence · lightspeed-core/lightspeed-stack-rhel9 as a component of Lightspeed Core · mta/mta-solution-server-rhel9 as a component of Migration Toolkit for Applications 8

Full record on NVD

Description

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.1, Authlib's OctKey.import_key() and HMAC signing and verification path accept zero-length key material. If an application's secret lookup can return an empty string or empty bytes, a remote attacker can compute the deterministic HS256, HS384, or HS512 signature for arbitrary token claims and have Authlib treat the token as authentic. This issue is fixed in version 1.9.1.

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Published
2026-10-22
Last Modified
2026-10-22

Frequently asked questions

What is CVE-2026-114616?

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.1, Authlib's OctKey.import_key() and HMAC signing and verification path accept zero-length key material. If an application's secret lookup can return an empty string or empty bytes, a remote attacker can compute the deterministic HS256, HS384, or HS512 signature for arbitrary token claims and have Authlib treat the token as authentic. This issue is fixed in version 1.9.1.

Is CVE-2026-114616 actively exploited?

Active exploitation of CVE-2026-114616 has not been confirmed.

What is the CVSS score for CVE-2026-114616?

CVE-2026-114616 has a CVSS v3 base score of 7.4 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.

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