Description
A vulnerability was found in vLLM up to 0.19.0. The affected element is the function has_mamba_layers of the file vllm/v1/kv_cache_interface.py of the component KV Block Handler. Performing a manipulation results in uninitialized resource. It is possible to initiate the attack remotely. The attack is considered to have high complexity. The exploitability is described as difficult. The exploit has been made public and could be used. The existence of this vulnerability is still disputed at present. The proposed patch did not fix the issue. A 3rd party explains: "The divergence could be explained by a benign and expected vLLM behavior where vLLM server could group concurrent requests together resulting in different input shapes based on varying request arrival time. The differences in grouped input shapes could call different kernels with could produce difference results due to rounding and differences in order of operations. There is an environment variable VLLM_BATCH_INVARIANT=1 for users that desire to have deterministic output with temperature 0.0."
Published: 2026-04-27
Score: 6.3 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

An uninitialized resource vulnerability exists in the has_mamba_layers function of the KV Block kv_cache_interface module in vllm up to version 0.19.0. By manipulating the input that feeds this function, an attacker can trigger an undefined memory state. This can lead to unpredictable behavior such as crashes or data corruption. The description indicates the exploit is possible remotely, has a high complexity and is difficult to execute, and that the vulnerability’s existence remains disputed. A proposed patch did not resolve the issue, and a third‑party analysis suggests the behavior may be benign under certain deterministic settings controlled by the VLLM_BATCH_INVARIANT variable.

Affected Systems

The issue affects the open‑source vllm project for all releases up to version 0.19.0. The affected component is the KV Block kv_cache_interface module located in vllm/v1/kv_cache_interface.py. Systems running 0.19.0 or earlier are vulnerable; newer versions contain the fix.

Risk and Exploitability

The risk is moderate due to the CVSS score of 6.3. Because the vulnerability is not listed in the CISA KEV catalog, the EPSS score of <1% indicates a very low probability of exploitation, but the exact probability remains uncertain. Attackers could leverage remote input to trigger the uninitialized state, which may compromise integrity or availability.

Generated by OpenCVE AI on August 26, 2026 at 06:36 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Apply the latest official release of vllm that includes a fix for the uninitialized resource, if available; otherwise, monitor for an official patch.
  • If an immediate upgrade is not possible, restrict or disable the remote KV block handler interface so that it can only be accessed from trusted IPs or by authenticated users.
  • Audit any custom code that calls has_mamba_layers to ensure all resources are fully initialized before use and monitor logs for abnormal cache errors that may indicate exploitation attempts.

Generated by OpenCVE AI on August 26, 2026 at 06:36 UTC.

Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-x368-4g9h-fvv4 vLLM makes Use of Uninitialized Resource
History

Tue, 25 Aug 2026 19:30:00 +0000

Type Values Removed Values Added
Description A vulnerability was found in vllm up to 0.19.0. The affected element is the function has_mamba_layers of the file vllm/v1/kv_cache_interface.py of the component KV Block Handler. Performing a manipulation results in uninitialized resource. It is possible to initiate the attack remotely. The attack is considered to have high complexity. The exploitability is described as difficult. The exploit has been made public and could be used. The patch is named 1ad67864c0c20f167929e64c875f5c28e1aad9fd. To fix this issue, it is recommended to deploy a patch. A vulnerability was found in vLLM up to 0.19.0. The affected element is the function has_mamba_layers of the file vllm/v1/kv_cache_interface.py of the component KV Block Handler. Performing a manipulation results in uninitialized resource. It is possible to initiate the attack remotely. The attack is considered to have high complexity. The exploitability is described as difficult. The exploit has been made public and could be used. The existence of this vulnerability is still disputed at present. The proposed patch did not fix the issue. A 3rd party explains: "The divergence could be explained by a benign and expected vLLM behavior where vLLM server could group concurrent requests together resulting in different input shapes based on varying request arrival time. The differences in grouped input shapes could call different kernels with could produce difference results due to rounding and differences in order of operations. There is an environment variable VLLM_BATCH_INVARIANT=1 for users that desire to have deterministic output with temperature 0.0."
Title vllm KV Block kv_cache_interface.py has_mamba_layers uninitialized resource vLLM KV Block kv_cache_interface.py has_mamba_layers uninitialized resource
References
Metrics cvssV2_0

{'score': 5.1, 'vector': 'AV:N/AC:H/Au:N/C:P/I:P/A:P/E:POC/RL:OF/RC:C'}

cvssV3_0

{'score': 5.6, 'vector': 'CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C'}

cvssV3_1

{'score': 5.6, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C'}

 cvssV2_0

{'score': 5.1, 'vector': 'AV:N/AC:H/Au:N/C:P/I:P/A:P/E:POC/RL:U/RC:UR'}

cvssV3_0

{'score': 5.6, 'vector': 'CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:U/RC:R'}

cvssV3_1

{'score': 5.6, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:U/RC:R'}

Tue, 28 Apr 2026 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 threat_severity

Moderate

Mon, 27 Apr 2026 18:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Mon, 27 Apr 2026 17:15:00 +0000

Type Values Removed Values Added
Description A vulnerability was found in vllm up to 0.19.0. The affected element is the function has_mamba_layers of the file vllm/v1/kv_cache_interface.py of the component KV Block Handler. Performing a manipulation results in uninitialized resource. It is possible to initiate the attack remotely. The attack is considered to have high complexity. The exploitability is described as difficult. The exploit has been made public and could be used. The patch is named 1ad67864c0c20f167929e64c875f5c28e1aad9fd. To fix this issue, it is recommended to deploy a patch.
Title vllm KV Block kv_cache_interface.py has_mamba_layers uninitialized resource
First Time appeared Vllm
Vllm vllm
Weaknesses CWE-908
CPEs cpe:2.3:a:vllm:vllm:*:*:*:*:*:*:*:*
Vendors & Products Vllm
Vllm vllm
References
Metrics cvssV2_0

{'score': 5.1, 'vector': 'AV:N/AC:H/Au:N/C:P/I:P/A:P/E:POC/RL:OF/RC:C'}

cvssV3_0

{'score': 5.6, 'vector': 'CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C'}

cvssV3_1

{'score': 5.6, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C'}

cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P'}

Subscriptions

Vllm Vllm
cve-icon MITRE

Status: PUBLISHED

Assigner: VulDB

Published:

Updated: 2026-08-25T19:07:56.947Z

Reserved: 2026-04-26T19:38:00.529Z

Link: CVE-2026-7141

cve-icon Vulnrichment

Updated: 2026-04-27T17:41:14.509Z

cve-icon NVD

Status : Modified

Published: 2026-04-27T17:16:45.637

Modified: 2026-08-25T20:17:08.387

Link: CVE-2026-7141

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-04-27T16:45:12Z

Links: CVE-2026-7141 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-08-26T06:45:03Z

Weaknesses
  • CWE-908

    Use of Uninitialized Resource