CVE-2026-73555: Environment and Information Disclosure via Exception Handling in vLLM
Vulnerability ID: CVE-2026-73555
CVSS Score: 5.3
Published: 2026-09-04
An information disclosure vulnerability in vLLM prior to version 0.26.0 allows unauthenticated remote attackers to trigger validation errors that expose highly sensitive host machine metadata, absolute paths, environment structures, and usernames. This flaw stems from improper serialization of Pydantic exceptions and an inadequate fallback sanitization function.
TL;DR
Unauthenticated remote attackers can query vLLM API endpoints with malformed JSON to retrieve full system paths, virtual environment directory structures, and host usernames from error tracebacks.
⚠️ Exploit Status: POC
Technical Details
- CWE ID: CWE-209
- Attack Vector: Network (AV:N)
- CVSS v3.1: 5.3 (Medium)
- EPSS Score: 0.00255
- Impact: Information Disclosure
- Exploit Status: poc
- KEV Status: Not Listed
Affected Systems
- vLLM API Server deployments running version < 0.26.0
-
vllm: < 0.26.0 (Fixed in:
0.26.0)
Code Analysis
Commit: e875216
Rebuild error formatting and harden fallback sanitization logic inside api_utils and server_utils
Mitigation Strategies
- Upgrade vLLM to version 0.26.0 or above to remediate path and context leak vectors.
- Implement a reverse proxy or Web Application Firewall (WAF) to filter detailed response payloads containing tracebacks.
- Configure container boundaries to utilize non-privileged usernames and run within virtual isolated roots like scratch directories.
Remediation Steps:
- Identify all current deployments of vLLM utilizing versions prior to 0.26.0.
- Update requirements and pull the latest v0.26.0 container images or python packages.
- Verify the remediation by sending a malformed request to
/v1/chat/completionsand ensuring no absolute file paths are returned in the response payload.
References
Read the full report for CVE-2026-73555 on our website for more details including interactive diagrams and full exploit analysis.
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