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CVE-2026-56104

33
FAUCET Score

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.

First published: Jun 22, 2026Last modified: Jul 14, 2026

Impacted Technologies

VendorProductVersion(s)CPE
>= 0, < 2.10.1CPE match
cpe:2.3:a:chainlit:chainlit:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

8.8HIGH

CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
VS Confidentiality
HIGH
VS Integrity
HIGH
VS Availability
NONE
SS Confidentiality
NONE
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.26%
Probability of exploitation in next 30 days
EPSS Percentile
17.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0026 is in the 6th percentile among its peer group of 1,162 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

github.com / Chainlit/chainlit/commit/5effb664f1e0af4a4f0a42fe63ea979676039a7f
github.com / Chainlit/chainlit/pull/2857
github.com / Chainlit/chainlit/releases/tag/2.10.1
vulncheck.com / advisories/chainlit-session-hijacking-via-websocket-session-restoration