CVE-2026-26717

State: Published
Severity: 4.8 Medium
Published: Feb 25, 2026
Updated: Feb 26, 2026
Reserved: Feb 16, 2026

Description

An issue in OpenFUN Richie (LMS) in src/richie/apps/courses/api.py. The application used the non-constant time == operator for HMAC signature verification in the sync_course_run_from_request function. This allows remote attackers to forge valid signatures and bypass authentication by measuring response time discrepancies

Scores

CVSS	Score	Vector	Source
3.1	4.8 Medium	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N	CISA-ADP

Weaknesses

CWE-208 Observable Timing Discrepancy

Affected Products

Product	Versions
n/an/a	n/aAffected

References

https://github.com/openfun/richie/commit/a1b5bbda3403d7debb466c303a32852925fcba5f
https://github.com/Rickidevs/CVE-2026-26717
https://medium.com/@ordogh/cve-2026-26717-hmac-timing-attack-in-openfun-richie-lms-f04377efe83d?postPublishedType=repub

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