Vulnerability in vllm (CVE-2026-73558)
Summary
Vulnerability in vllm (CVE-2026-73558). Confidential information can be exposed externally. Mitigation: upgrade to 0.27.0 or later.
Original description
The description as published by the source.
Summary
An integer overflow in the act_and_mul_kernel kernel can cause the output of one user request to be incorporated into the response of another request within the same inference batch. Under certain conditions, the last request in a batch can receive a partial or complete copy of the first user's inference result, resulting in cross-user data leakage.
Details
The root cause is an integer overflow in the expression blockIdx.x * 2 * d at https://github.com/vllm-project/vllm/blob/ff712f6447093d07747c88680b9d006b119f5890/csrc/activation_kernels.cu#L82.
As a result, the computation for one user (User A) can incorrectly consume input data from another user (User B). In particular, when 2^32 is divisible by d, the overflow can cause User A's output to contain portions of User B's inference result. In some cases, User B's response may be copied entirely into User A's response.
This constitutes a severe cross-user information disclosure vulnerability and is straightforward to trigger.
PoC
We reproduced the issue using meta-llama/Llama-3.2-1B-Instruct, for which d = 8192.
Using the following configuration:
Batch size: 17
Sequence length: 16384
The final response in the batch becomes an exact copy of the first response in the batch, demonstrating complete cross-user data leakage.
Impact
This vulnerability enables cross-user information disclosure. An attacker can intentionally craft requests that are processed within the same inference batch as a victim's r…
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-2026-73558 has been found in vllm.
Confidential information can be exposed externally. CVSS score: 5.3/10.
What to do: upgrade vllm to 0.27.0 or later.
If unsure, ask your IT team or search "vllm CVE-2026-73558" on the vendor's site.
CVE-2026-73558 (vllm) — CWE-190 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated
Patched: 0.27.0 — apply immediately
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-190) exists in vllm.
Check the vendor advisory for the affected versions of vllm.
Severity: Medium (CVSS 5.3/10). Confidential information can be exposed externally.
Update to 0.27.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
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
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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 patch patch
Upgrade vllm to 0.27.0ステージング環境で 0.27.0 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。
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3Post-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 github.com
- web nvd.nist.gov
- web github.com