CVE-2026-26717
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...
- Published
- Feb 25, 2026
- Updated
- Feb 26, 2026
- Assigning CNA
- mitre
- Evidence observed
- Aug 25, 2026
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:NLow · next 30 days
- Percentile
- 31.3%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
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
Sources
1- CVE-2026-26717Research
Technical write-up of CVE-2026-26717, an HMAC timing attack in OpenFUN Richie LMS webhook authentication, including vulnerable code, impact, and fix using hmac.compare_digest.
Responsible use
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