Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Richie (OpenFUN) versions before 3.3.0 are affected. The sync_course_run_from_request function compares HMAC signatures with a non-constant-time equality operator, so a remote attacker who can measure response timing differences may be able to forge valid signatures and bypass authentication. Upgrade to richie 3.3.0 or later.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 4.8 | Medium | 3.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N | GitHub Advisory Database |
- CISA KEV Not listed.
- EPSS 0.0044, the 38th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:34 UTC First seen by agentprime
- 31 Oct 2026, 14:34 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-xjhr-fm27-4hmx
- OSV: GHSA-xjhr-fm27-4hmx
- nvd.nist.gov/vuln/detail/CVE-2026-26717
- github.com/openfun/richie/commit/a1b5bbda3403d7debb466c303a32852925fcba5f
- github.com/Rickidevs/CVE-2026-26717
- github.com/openfun/richie
- medium.com/@ordogh/cve-2026-26717-hmac-timing-attack-in-openfun-richie-lms-f04377efe83d?postPublishedType=repub