CVE-2026-26717

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

Affected Software

Weaknesses

• n/a

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: poc
  • Automatable: no
  • Technical Impact: partial

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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