Vulnerability-Lookup

CVE-2026-86099 (GCVE-0-2026-86099)

Vulnerability from cvelistv5 – Published: 2026-09-09 13:31 – Updated: 2026-09-09 14:49

Title

Chainlit through 2.12.0 Path Traversal via socket.io sessionId

Summary

Chainlit through 2.12.0 fails to validate the client-supplied socket.io sessionId parameter, allowing unauthenticated attackers to traverse filesystem paths by injecting absolute or relative path sequences. Attackers can craft malicious sessionId values that escape the upload directory and recursively delete arbitrary directories accessible to the service process.

Severity

8.8 (High)


                        
                          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

8.2 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-09 14:47 UTC

CWE

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

Assigner

VulnCheck mitre root

References

5 references

URL	Tags
https://github.com/Chainlit/chainlit	product
https://github.com/Chainlit/chainlit/blob/2.12.0/…	technical-description
https://github.com/Chainlit/chainlit/blob/2.12.0/…	technical-description
https://pypi.org/project/chainlit/	product
https://www.vulncheck.com/advisories/chainlit-thr…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version	CPE status
Chainlit	chainlit	Affected: 0 , ≤ 2.12.0 (semver) cpe:2.3:a:chainlit:chainlit::::::::

Date Public

2026-09-03 00:00

Credits

mil4n

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-86099

Vulnerability from fkie_nvd - Published: 2026-09-09 14:17 - Updated: 2026-09-09 20:20

Severity

8.2 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Summary

References

	URL	Tags
	disclosure@vulncheck.com	https://github.com/Chainlit/chainlit
	disclosure@vulncheck.com	https://github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/session.py
	disclosure@vulncheck.com	https://github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/socket.py
	disclosure@vulncheck.com	https://pypi.org/project/chainlit/
	disclosure@vulncheck.com	https://www.vulncheck.com/advisories/chainlit-through-2.12.0-path-traversal-via-socket-io-sessionid

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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        }
      ],
      "source": "disclosure@vulncheck.com",
      "type": "Secondary"
    }
  ]
}

GHSA-WF68-H55H-FVXV

Vulnerability from github – Published: 2026-09-09 15:35 – Updated: 2026-09-09 15:35

Details

Severity

8.2 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

8.8 (High)


                  
                    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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-86099"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-09T14:17:20Z",
    "severity": "HIGH"
  },
  "details": "Chainlit through 2.12.0 fails to validate the client-supplied socket.io sessionId parameter, allowing unauthenticated attackers to traverse filesystem paths by injecting absolute or relative path sequences. Attackers can craft malicious sessionId values that escape the upload directory and recursively delete arbitrary directories accessible to the service process.",
  "id": "GHSA-wf68-h55h-fvxv",
  "modified": "2026-09-09T15:35:11Z",
  "published": "2026-09-09T15:35:11Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-86099"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Chainlit/chainlit"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/session.py"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Chainlit/chainlit/blob/2.12.0/backend/chainlit/socket.py"
    },
    {
      "type": "WEB",
      "url": "https://pypi.org/project/chainlit"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/chainlit-through-2.12.0-path-traversal-via-socket-io-sessionid"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

CVE-2026-86099 (GCVE-0-2026-86099)

FKIE_CVE-2026-86099

GHSA-WF68-H55H-FVXV

Tags

Sightings

Nomenclature