CVE-2026-52132
Received Received - Intake

Denial of Service in llama.cpp via Negative top_n Parameter

Publication date: 2026-09-01

Last updated on: 2026-09-01

Assigner: MITRE

Description
llama.cpp through commit 97f06e9, when started with the --reranking flag, allows remote attackers to cause a denial of service (std::bad_alloc and HTTP 500) via a negative top_n value in a POST request to /rerank.

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Meta Information

Published
2026-09-01
Last Modified
2026-09-01
Generated
2026-09-01
AI Q&A
2026-09-01
EPSS Evaluated
N/A
NVD
CVE-2026-52132
EUVD
EUVD-2026-69410

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
llama_cpp llama_cpp From 97f06e9 (inc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in llama.cpp occurs when the application is started with the --reranking flag. It allows remote attackers to cause a denial of service by sending a POST request to /rerank with a negative top_n value. This triggers a std::bad_alloc error and results in an HTTP 500 response.

Detection Guidance

Monitor HTTP 500 errors from /rerank endpoints when negative top_n values are submitted. Check server logs for std::bad_alloc exceptions in llama.cpp processes running with --reranking flag.

Impact Analysis

The vulnerability can cause your llama.cpp service to crash or become unavailable due to the denial of service. This may disrupt services relying on the /rerank endpoint, leading to downtime or degraded performance.

Mitigation Strategies

Disable the --reranking flag if not required. Implement input validation to reject negative top_n values in POST /rerank requests. Update to a patched version once available.

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