CVE-2026-26717 json
OpenFUN Richie Observable Timing Discrepancy in its sync_course_run_from_request function
published 2026-02-25 8 mo ago modified 2026-09-10 1 mo ago also GHSA-xjhr-fm27-4hmx , PYSEC-2026-3052 , EUVD-2026-8680
- cvss
- 4.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 38%
- public exploits
- 0
- none known
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
Patch / fix
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- 8 mo ago
Exploit prediction
0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CISA ADP | 3.1 | 4.8 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N |
| CNA | 3.1 | 4.8 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N |
| OSV | 3.1 | 4.8 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N |
| GitHub | 3.1 | 4.8 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | richie | <3.3.0 |
3.3.0 |
Classification
- Weakness
-
- CWE-208 Observable Timing Discrepancy
References
-
github.com
/openfun/richie/commit/a1b5bbda3403d7debb466c303a32852925fcba5f
web
-
github.com
/Rickidevs/CVE-2026-26717
web
-
medium.com
/@ordogh/cve-2026-26717-hmac-timing-attack-in-openfun-richie-lms-f04377efe83d?postPublishedType=repub
web
-
nvd.nist.gov
/vuln/detail/CVE-2026-26717
advisory
-
github.com
/openfun/richie
package
-
pypi.org
/project/richie
package
-
github.com
/advisories/GHSA-xjhr-fm27-4hmx
advisory
Sources
- CVE List CVE-2026-26717
- GitHub Advisory GHSA-xjhr-fm27-4hmx
- NVD CVE-2026-26717
- OSV PYSEC-2026-3052
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.