CVE-2026-86099

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

• ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.59% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 48.4% of scored records. A rank, not a probability.

NVD base score

8.8 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/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

NVD analysis status

Deferred. NVD last modified this record on 2026-09-09.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2026-09-09 13:31Z1 MO AGO

Last updated

2026-09-09 14:49Z1 MO AGO

Reserved

2026-09-04

Assigning CNA

VulnCheck

Record state

PUBLISHED

Severity

High (CVSS 8.8)

CNA CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N

Weaknesses

• CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')Base

Data version

5.2

Document digest

c99bbe133fc29524c6c3beff1026e52682a1dac78d2f4df5782feb9cd17c0a9a

• github.comProduct Repositoryhttps://github.com/Chainlit/chainlitproduct
• github.comVulnerable files_dir property and rmtree sinkhttps://github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/session.pytechnical-description
• github.comClient-supplied sessionId assignmenthttps://github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/socket.pytechnical-description
• pypi.orgPyPI Packagehttps://pypi.org/project/chainlit/product
• www.vulncheck.comVulnCheck Advisory: Chainlit through 2.12.0 Path Traversal via socket.io sessionIdhttps://www.vulncheck.com/advisories/chainlit-through-2.12.0-path-traversal-via-socket-io-sessionidthird-party-advisory