CVE-2026-43628

Received Received - Intake

Integer Underflow in llama.cpp DRY Sampler

Publication date: 2026-08-06

Last updated on: 2026-08-06

Assigner: VulnCheck

Description

llama.cpp builds b3978 through b9058 contain an integer underflow and out-of-bounds read vulnerability in the DRY sampler that allows unauthenticated attackers to trigger a heap buffer underflow by sending a crafted HTTP request with dry_allowed_length set to INT32_MIN to the /v1/completions or /v1/chat/completions endpoints. Attackers can exploit this vulnerability to crash the server with SIGSEGV causing denial of service for all connected users, or corrupt token sampling probabilities by reading garbage values from memory before the allocated buffer.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-06

Last Modified

2026-08-06

Generated

2026-08-07

AI Q&A

2026-08-07

EPSS Evaluated

N/A

NVD

CVE-2026-43628

Affected Vendors & Products

Vendor	Product	Version / Range
llama_cpp	llama_cpp	From b3978 (inc) to b9058 (inc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-191	The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
CWE-125	The product reads data past the end, or before the beginning, of the intended buffer.

Attack-Flow Graph

Executive Summary

This vulnerability is an integer underflow and out-of-bounds read issue in llama.cpp versions b3978 through b9058. It affects the DRY sampler and can be triggered by sending a crafted HTTP request with dry_allowed_length set to INT32_MIN to the /v1/completions or /v1/chat/completions endpoints. This causes a heap buffer underflow, leading to potential denial of service or memory corruption.

Detection Guidance

This vulnerability can be detected by monitoring for crashes or SIGSEGV errors in the llama.cpp server when processing requests with dry_allowed_length set to INT32_MIN. Check server logs for segmentation faults or unexpected terminations during HTTP request handling.

Impact Analysis

Attackers can exploit this to crash the server with SIGSEGV, causing a denial of service for all users. Additionally, it may corrupt token sampling probabilities by reading invalid memory values, potentially affecting the integrity of generated outputs.

Compliance Impact

This vulnerability could potentially impact compliance with GDPR and HIPAA by enabling denial-of-service attacks that disrupt service availability or by exposing sensitive data through memory corruption. However, specific compliance implications depend on system configuration and data processing context.

Mitigation Strategies

Update llama.cpp to a version beyond b9058 to address the integer underflow and out-of-bounds read vulnerability in the DRY sampler.

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