PT-2026-51339 · Chainlit · Chainlit

Tanguy Snoeck · Published 2026-06-22 · Updated 2026-06-22 · CVE-2026-56104

Positive Technologies (AI Summary)

CVSS v3.1

7.4

High

Base vector

AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Name of the Vulnerable Software and Affected Versions Chainlit versions prior to 2.10.1

Description An issue exists where unauthenticated attackers can restore and inherit authenticated user sessions. This occurs during WebSocket session restoration when a valid sessionId is presented without ownership verification via the 'restore existing session' path. Successful exploitation allows an attacker to assume a victim's permissions and roles, leading to unauthorized access to restricted data and the ability to invoke tools.

Recommendations Update to version 2.10.1 or later.

Fix

Missing Authorization

Weakness Enumeration

CWE-862

Related Identifiers

CVE-2026-56104

Affected Products

Chainlit

References · 6

• https://nvd.nist.gov/vuln/detail/CVE-2026-56104 · Security Note
• https://github.com/Chainlit/chainlit/commit/5effb664f1e0af4a4f0a42fe63ea979676039a7f · Patch
• https://vulncheck.com/advisories/chainlit-session-hijacking-via-websocket-session-restoration · Note
• https://github.com/Chainlit/chainlit/releases/tag/2.10.1 · Note
• https://twitter.com/VulmonFeeds/status/2069148845347381304 · Twitter Post
• https://github.com/Chainlit/chainlit/pull/2857 · Note