CVE-2026-73558

vLLM: Cross-User Data Leak Vulnerability

MEDIUM
5.3
CVSS Score
Published: August 13, 2026 at 03:06 PM UTC
Updated: September 28, 2026 at 06:41 PM UTC
1 product affected across 1 vendorvLLM

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.4%
SSVC
PoC

Description

vLLM is an inference and serving engine for large language models. Prior to 0.27.0, an integer overflow in blockIdx.x * 2 * d in activation_kernels.cu can cause act_and_mul_kernel to consume another batched user's input, allowing a request processed in the same inference batch to receive a partial or complete copy of another user's inference result. This issue is fixed in version 0.27.0.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 0.27.0
Affected range stops below 0.27.0, so it looks safe — our inference, not a vendor statement

References (5)

x_refsource_CONFIRMExploitVendor Advisory
Source: cverecord
https://github.com/vllm-project/vllm/security/advisories/GHSA-7m6h-x95x-82q5
x_refsource_MISCIssue TrackingPatch
Source: cverecord
https://github.com/vllm-project/vllm/issues/42860
x_refsource_MISCIssue TrackingPatch
Source: cverecord
https://github.com/vllm-project/vllm/pull/49660
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/vllm-project/vllm/releases/tag/v0.27.0

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-190

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