CVE-2026-56340

CVE-2026-56340 is a high-severity improper input validation vulnerability in vllm (pip), affecting versions >= 0.10.2, < 0.13.0. It is fixed in 0.13.0.

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Summary

vLLM introduced enhanced protection for CVE-2025-62164

The fix here for CVE-2025-62164 is not sufficient. The fix only disables prompt embeds by default rather than addressing the root cause, so the DoS vulnerability remains when the feature is enabled.

Details

vLLM's pending change attempts to fix the root cause, which is the missing sparse tensor validation. PyTorch (~v2.0) disables sparse tensor validation (specifically, sparse tensor invariants checks) by default for performance reasons. vLLM is adding the sparse tensor validation to ensure indices are valid, non-negative, and within bounds. These checks help catch malformed tensors.

PoC

NA

Changes

Impact

Current fix only added a flag to disable/enable prompt embeds, so by default, prompt embeds feature is disabled in vLLM, which stops DoS attacks through the embeddings. However, It doesn’t address the problem when the flag is enabled and there is still potential for DoS attacks.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2026-56340 has a CVSS score of 8.8 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.13.0); upgrading removes the vulnerable code path.

Affected versions

vllm (>= 0.10.2, < 0.13.0)

Security releases

vllm → 0.13.0 (pip)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

Upgrade vllm to 0.13.0 or later to resolve this vulnerability.

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

  1. What is CVE-2026-56340? CVE-2026-56340 is a high-severity improper input validation vulnerability in vllm (pip), affecting versions >= 0.10.2, < 0.13.0. It is fixed in 0.13.0. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
  2. How severe is CVE-2026-56340? CVE-2026-56340 has a CVSS score of 8.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
  3. Which versions of vllm are affected by CVE-2026-56340? vllm (pip) versions >= 0.10.2, < 0.13.0 is affected.
  4. Is there a fix for CVE-2026-56340? Yes. CVE-2026-56340 is fixed in 0.13.0. Upgrade to this version or later.
  5. Is CVE-2026-56340 exploitable, and should I be worried? Whether CVE-2026-56340 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
  6. What actually determines whether CVE-2026-56340 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
  7. How do I fix CVE-2026-56340? Upgrade vllm to 0.13.0 or later.

Other vulnerabilities in vllm

CVE-IDSeverityPackage summary
CVE-2026-105753Mediumvllm: vLLM: Mirrored multimodal IPC caches desync after a rejected request — a later request reusing the same media hash trips a receiver…CVE-2026-105752Lowvllm: vLLM: Harmony tool continuations drop `cache_salt` — restoring a cross-tenant prefix-cache membership oracleCVE-2026-105758Mediumvllm: vLLM: Qwen2-VL / Qwen3-VL video samplers bound on request-controlled max_frames, which the num_frames ceiling does not reachCVE-2026-105760Mediumvllm: vLLM: GLMGA video sampling permits request-driven CPU and memory exhaustionCVE-2026-105754Mediumvllm: vLLM: Scale-out disaggregated multimodal transport trusts caller-supplied features

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