# CVE-2026-54236: vLLM: incomplete CVE-2026-22778 fix leaks PIL repr addresses via Anthropic router

> An unauthenticated attacker can leak heap memory addresses via error messages in the Anthropic API router by sending malformed image data.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 22 Jun 2026
- **Updated:** 23 Jun 2026
- **Also known as:** GHSA-hgg8-fqqc-vfmw, MINI-3j4q-6399-w2vj, MINI-9gcq-m48c-c3rr, MINI-jvqw-774c-mmp8, PYSEC-2026-3408

## What is CVE-2026-54236?

CVE-2026-54236 is a medium-severity vulnerability in Vllm Vllm, published on 22 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

vLLM is an inference and serving engine for large language models (LLMs). Prior to 0.23.1rc0, the fix for CVE-2026-22778, which introduced a sanitize_message helper that strips object-repr memory addresses from error messages before they reach the client, is incomplete: several response paths echo str(exc) directly to clients without calling sanitize_message. The unsanitized sites include the Anthropic API router in vllm/entrypoints/anthropic/api_router.py (the POST /v1/messages and POST /v1/messages/count_tokens handlers), the Server-Sent Events streaming converter in vllm/entrypoints/anthropic/serving.py, and the realtime speech-to-text WebSocket in vllm/entrypoints/speech_to_text/realtime/connection.py. These paths catch the exception inside the route coroutine and construct the JSONResponse themselves, bypassing the sanitizing global FastAPI exception handler, and WebSocket frames do not traverse that handler chain at all. Using the same primitive as the parent issue, an unauthenticated attacker can send malformed image bytes through the Anthropic Messages API image content parts so that PIL.Image.open raises an UnidentifiedImageError whose message contains the BytesIO object repr, leaking the heap memory address verbatim in the error.message field of the response body. This vulnerability is fixed in 0.23.1rc0.

Weakness: CWE-532 (Insertion of Sensitive Information into Log File)

## Which versions are affected by CVE-2026-54236?

3 open source packages ship an affected version, including vllm. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `vllm` | PyPI | All versions to 0.23.0 | None |
| `vllm` | PyPI | All versions | 0.24.0 |
| `vllm` | PyPI | All versions | 0.24.0 |

Products: Vllm Vllm.

## How do I fix CVE-2026-54236?

Upgrade vllm to 0.24.0 or later.

## Is CVE-2026-54236 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54236 exists.

Public exploit code:

- vLLM <= 0.23.0 - Anthropic Router Heap Address Information Leak (nuclei): http/cves/2026/CVE-2026-54236.yaml

## Other vulnerabilities in Vllm Vllm

- [CVE-2025-32444](https://insights.sbomify.com/CVE-2025-32444/): vLLM Vulnerable to Remote Code Execution via Mooncake Integration (critical 10.0)
- [CVE-2026-22778](https://insights.sbomify.com/CVE-2026-22778/): vLLM leaks a heap address when PIL throws an error (critical 9.8)
- [CVE-2025-47277](https://insights.sbomify.com/CVE-2025-47277/): vLLM Allows Remote Code Execution via PyNcclPipe Communication Service (critical 9.8)
- [CVE-2024-11041](https://insights.sbomify.com/CVE-2024-11041/): Remote Code Execution in vllm-project/vllm (critical 9.8)
- [CVE-2026-48746](https://insights.sbomify.com/CVE-2026-48746/): vLLM: OpenAI auth bypass (critical 9.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54236 and fix it if it is affected.

What it is: CVE-2026-54236 is a medium-severity vulnerability in Vllm Vllm, published on 22 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54236 exists.

Affected packages and fixed versions:
- vllm (PyPI): affected all versions up to 0.23.0; no fix listed
- vllm (PyPI): affected all versions; fixed in 0.24.0
- vllm (PyPI): affected all versions; fixed in 0.24.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-54236/ (Markdown: https://insights.sbomify.com/CVE-2026-54236/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54236
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54236
- OSV: https://osv.dev/vulnerability/CVE-2026-54236

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54236/
Summaries are generated and may contain mistakes; the official description above is the record.