CVE-2026-34756

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Source
https://cve.org/CVERecord?id=CVE-2026-34756
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-34756.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-34756
Aliases
Related
Published
2026-04-06T15:40:03.448Z
Modified
2026-07-09T03:51:25.408116628Z
Severity
  • 6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
vLLM Affected by Unauthenticated OOM Denial of Service via Unbounded `n` Parameter in OpenAI API Server
Details

vLLM is an inference and serving engine for large language models (LLMs). From 0.1.0 to before 0.19.0, a Denial of Service vulnerability exists in the vLLM OpenAI-compatible API server. Due to the lack of an upper bound validation on the n parameter in the ChatCompletionRequest and CompletionRequest Pydantic models, an unauthenticated attacker can send a single HTTP request with an astronomically large n value. This completely blocks the Python asyncio event loop and causes immediate Out-Of-Memory crashes by allocating millions of request object copies in the heap before the request even reaches the scheduling queue. This vulnerability is fixed in 0.19.0.

Database specific 
{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34756.json",
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-770"
    ]
}
References

Affected packages

Git / github.com/vllm-project/vllm

Affected ranges

Type
GIT
Repo
https://github.com/vllm-project/vllm
Events
Introduced
67d96c29fba9b72cb4c4edbc26211c208a00ebdd
Fixed
2a69949bdadf0e8942b7a1619b229cb475beef20
Fixed
b111f8a61f100fdca08706f41f29ef3548de7380
Database specific 
{
    "source": [
        "CPE_RANGE",
        "REFERENCES"
    ],
    "cpe": "cpe:2.3:a:vllm:vllm:*:*:*:*:*:*:*:*",
    "extracted_events": [
        {
            "introduced": "0.1.0"
        },
        {
            "fixed": "0.19.0"
        }
    ]
}

Affected versions

v0.*
v0.1.0
v0.1.1
v0.1.2
v0.1.3
v0.1.4
v0.1.5
v0.1.6
v0.1.7
v0.10.0
v0.10.0rc1
v0.10.0rc2
v0.10.1rc1
v0.10.2rc1
v0.10.2rc2
v0.11.0rc1
v0.11.1
v0.11.1rc0
v0.11.1rc1
v0.11.1rc2
v0.11.1rc3
v0.11.1rc4
v0.11.1rc5
v0.11.1rc6
v0.13.0rc1
v0.14.0rc0
v0.14.0rc1
v0.15.0rc1
v0.15.2rc0
v0.16.0rc0
v0.16.0rc1
v0.17.0rc0
v0.17.1rc0
v0.17.2rc0
v0.18.0rc0
v0.18.1rc0
v0.19.0rc0
v0.19.0rc1
v0.2.0
v0.2.1
v0.2.2
v0.2.3
v0.2.4
v0.2.5
v0.2.6
v0.2.7
v0.3.0
v0.3.1
v0.3.2
v0.3.3
v0.4.0
v0.4.0.post1
v0.4.1
v0.4.2
v0.4.3
v0.5.0
v0.5.0.post1
v0.5.1
v0.5.2
v0.5.3
v0.5.3.post1
v0.5.4
v0.5.5
v0.6.0
v0.6.1
v0.6.1.post1
v0.6.1.post2
v0.6.2
v0.6.3
v0.6.3.post1
v0.6.4
v0.6.4.post1
v0.6.5
v0.6.6
v0.6.6.post1
v0.7.0
v0.7.1
v0.7.2
v0.7.3
v0.8.0rc1
v0.8.0rc2
v0.8.1
v0.8.2
v0.8.3rc1
v0.8.4
v0.9.0
v0.9.1
v0.9.1rc1
v0.9.1rc2
v0.9.2rc1

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-34756.json"