---
id: CVE-2026-56104
aliases:
  - GHSA-c39v-8hrw-h448
title: Chainlit contains a session hijacking vulnerability
summary: Chainlit contains a session hijacking vulnerability
severity: high
cvss: 7.4
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'
vendor: chainlit
product: chainlit
ecosystem: pip
affected:
  - chainlit < 2.10.1
patched:
  - chainlit 2.10.1
published: '2026-06-22'
updated: '2026-09-21'
sourceUpdated: '2026-09-21T22:30:12.894277651Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-c39v-8hrw-h448'
references:
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-56104'
  - url: 'https://github.com/Chainlit/chainlit/pull/2857'
  - url: >-
      https://github.com/Chainlit/chainlit/commit/5effb664f1e0af4a4f0a42fe63ea979676039a7f
  - url: 'https://github.com/Chainlit/chainlit'
  - url: 'https://github.com/Chainlit/chainlit/releases/tag/2.10.1'
  - url: >-
      https://www.vulncheck.com/advisories/chainlit-session-hijacking-via-websocket-session-restoration
  - url: 'https://github.com/advisories/GHSA-c39v-8hrw-h448'
tags:
  - osv
  - pip
  - ghsa
epss: 0.00417
epssPercentile: 0.33318
cwe:
  - CWE-862
ingestedAt: '2026-09-21T22:54:37.976Z'
---

## Overview

Chainlit before 2.10.1 contains a session hijacking vulnerability that allows unauthenticated attackers to restore and inherit authenticated user sessions by presenting a valid sessionId during WebSocket session restoration without ownership verification. Attackers can exploit the restore_existing_session path to assume a victim's permissions and roles, enabling unauthorized invocation of tools and access to data restricted to the authenticated victim.

## Affected packages

- `chainlit < 2.10.1`

## Remediation

Upgrade to a patched release:

- `chainlit 2.10.1`