What is CVE-2026-82290?

CVE-2026-82290 is a medium-severity vulnerability in Chainlit, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 5.3/10. Published 2026-08-28.

How severe is CVE-2026-82290?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Auth bypass in Chainlit

CVE-2026-82290

Chainlit through 2.12.0 fails to validate ownership of feedback records in PUT and DELETE endpoints. Authenticated attackers can delete or modify other users' feedback by supplying arbitrary feedback identifiers, corrupting human-rating data used for model evaluation.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published 2026-08-28 · last modified 2026-09-16.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.003 (25.5th percentile), scored 2026-10-13.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 26th percentile — 25.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

Chainlit

Weakness classification (CWE)

CWE-639 — Authorization Bypass Through User-Controlled Key

References

GitHub Issue #2975 (issue-tracking)
github.com/Chainlit/chainlit (product)
Vulnerable code: server.py (technical-description)
VulnCheck Advisory: Chainlit Feedback Endpoints Missing Ownership Validation (third-party-advisory)

Frequently asked questions

What is CVE-2026-82290?: CVE-2026-82290 is a medium-severity vulnerability in Chainlit, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 5.3/10. Published 2026-08-28.
How severe is CVE-2026-82290?: Medium severity. CVSS v3 base score is 5.3 out of 10.