Is CVE-2026-73555 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-73555 being exploited in the wild.

How severe is CVE-2026-73555?

Medium severity, with a CVSS score of 5.3, published 13 August 2026.

Which products and versions are affected?

vllm (PyPI) ECOSYSTEM:introduced=0,fixed=0.26.0.

Is there a fix for CVE-2026-73555?

Yes. vllm (PyPI): upgrade to 0.26.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-73555 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-73555?

Check whether you run vllm (PyPI) or Vllm at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-73555: vLLM information disclosure via validation error messages

CVE-2026-73555 · Severity: medium · CVSS 5.3 · Published 2026-08-13

vLLM is an open-source LLM serving framework that provides an API for running large language models. When the API receives malformed requests, error messages inadvertently expose sensitive system information including the OS username, home directory path, Python version, and internal file paths. An unauthenticated attacker can trigger these errors with a single malformed HTTP request to any JSON-accepting endpoint, enabling reconnaissance and precise version fingerprinting to facilitate targeted exploits.

Technologies: vllm (PyPI), Vllm. Vendors: PyPI, Vllm.

Quick answers

Is CVE-2026-73555 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-73555 being exploited in the wild.
How severe is CVE-2026-73555?: Medium severity, with a CVSS score of 5.3, published 13 August 2026.
Which products and versions are affected?: vllm (PyPI) ECOSYSTEM:introduced=0,fixed=0.26.0.
Is there a fix for CVE-2026-73555?: Yes. vllm (PyPI): upgrade to 0.26.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-73555 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-73555?: Check whether you run vllm (PyPI) or Vllm at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

vllm (PyPI): upgrade to 0.26.0 or later
```
pip install "vllm>=0.26.0"
```

Technical details

The vulnerability is an information disclosure flaw (CWE-209) in vLLM's error handling. When FastAPI raises a Pydantic RequestValidationError for malformed JSON or missing required fields, the validation_exception_handler in vllm/entrypoints/openai/server_utils.py converts the exception to a string via str(exc), which includes internal file paths and line numbers. The existing sanitize_message() function strips memory addresses but does not filter File "...", line X patterns. This allows unauthenticated attackers to extract OS username, home directory path, virtual environment location, Python version, internal package structure, and handler function names—all prerequisites for targeted exploitation. The vulnerability affects all POST endpoints accepting JSON bodies including /v1/chat/completions, /v1/completions, /tokenize, and /detokenize. No authentication or user interaction is required. The fix (patched in version 0.26.0) involves either reconstructing error messages from structured Pydantic error lists rather than raw exception strings, or adding regex-based filtering to strip file path patterns.

Affected products

vLLM Project vLLM < 0.26.0

Identifiers

CVE-2026-73555
GHSA-hwrm-c4cx-rf4j
PYSEC-2026-3937

Timeline

2026-07-27: disclosed
2026-09-04: advisory
2026-09-04: patched: Fix released in vLLM v0.26.0

References

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