Vulnerability in vllm (CVE-2026-73555)
Summary
Vulnerability in vllm (CVE-2026-73555). Risk of unauthorized operations or information disclosure. Exploitable via RequestValidationError. Mitigation: upgrade to 0.26.0 or later.
Original description
The description as published by the source.
Summary
When the vLLM API receives a malformed request (e.g., invalid JSON or missing required fields), FastAPI raises a Pydantic RequestValidationError. The validation_exception_handler in vllm/entrypoints/openai/server_utils.py converts this exception to a string via str(exc), which includes the internal file path and line number of the handler function. The existing sanitize_message() function in vllm/entrypoints/utils.py strips memory addresses (e.g., 0x7f...) but does not strip File "...", line X patterns. The result is a user-facing HTTP response that leaks internal system information.
Impact
An unauthenticated attacker can extract the following with a single malformed request:
- OS username running the vLLM process (e.g.,
ubuntu) - Home directory path (e.g.,
/home/ubuntu/) - Virtual environment path (e.g.,
vllm-env/) - Python version (e.g.,
3.12) - Internal package structure and line numbers (e.g.,
vllm/entrypoints/openai/chat_completion/api_router.py) - Handler function names per endpoint, enabling precise version fingerprinting
This information aids attackers in constructing targeted exploits: environment paths narrow the attack surface, and handler function names + line numbers enable exact version identification even when the /version endpoint is disabled.
All POST endpoints that accept JSON bodies are affected, including /v1/chat/completions, /v1/completions, /tokenize, and /detokenize.
Wo…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-73555 has been found in vllm.
Attackers can target a specific entry point like RequestValidationError over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade vllm to 0.26.0 or later.
If unsure, ask your IT team or search "vllm CVE-2026-73555" on the vendor's site.
CVE-2026-73555 (vllm) — CWE-209 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: RequestValidationError / validation_exception_handler / ubuntu / sanitize_message
Patched: 0.26.0 — apply immediately
Workaround: Deploying vLLM behind a reverse proxy that rewrites error response bodies to strip file paths would mitigate this, though it is fragile.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-209) exists in vllm. Attackers reach the vulnerable code path via RequestValidationError without authentication.
Check the vendor advisory for the affected versions of vllm. Attack surface: RequestValidationError / validation_exception_handler / ubuntu / sanitize_message.
Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.
Update to 0.26.0.
Workaround: Deploying vLLM behind a reverse proxy that rewrites error response bodies to strip file paths would mitigate this, though it is fragile.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'vllm' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'vllm' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
vllmを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply temporary workaround mitigate
Deploying vLLM behind a reverse proxy that rewrites error response bodies to strip file paths would mitigate this, though it is fragile.パッチが適用されるまでの応急処置として、Deploying vLLM behind a reverse proxy that rewrites error response bodies to strip file paths would mitigate this, though it is fragile. を実施。回避策の副作用 (機能低下) を確認した上で。
-
3Apply patch patch
Upgrade vllm to 0.26.0ステージング環境で 0.26.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
4Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- web github.com
- web github.com
- web github.com
- web github.com
- web nvd.nist.gov
- web github.com