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AI / ML CVE-2026-21869

HIGH
Out-of-bounds Write (CWE-787)
2026-01-08 security-advisories@github.com
8.8
CVSS 3.1 · GitHub Advisory
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Severity by source

GitHub Advisory PRIMARY
8.8 HIGH
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
SUSE
HIGH
qualitative
Red Hat
8.1 HIGH
qualitative

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

3
Analysis Generated
Mar 12, 2026 - 21:54 vuln.today
PoC Detected
Feb 02, 2026 - 19:12 vuln.today
Public exploit code
CVE Published
Jan 08, 2026 - 00:16 nvd
HIGH 8.8

DescriptionGitHub Advisory

llama.cpp is an inference of several LLM models in C/C++. In commits 55d4206c8 and prior, the n_discard parameter is parsed directly from JSON input in the llama.cpp server's completion endpoints without validation to ensure it's non-negative. When a negative value is supplied and the context fills up, llama_memory_seq_rm/add receives a reversed range and negative offset, causing out-of-bounds memory writes in the token evaluation loop. This deterministic memory corruption can crash the process or enable remote code execution (RCE). There is no fix at the time of publication.

AnalysisAI

Llama.cpp server endpoints fail to validate the n_discard parameter from JSON input, allowing negative values that trigger out-of-bounds memory writes when the context buffer fills. This memory corruption vulnerability affects LLM inference operations and can be exploited remotely without authentication to crash the service or achieve code execution; public exploit code exists and no patch is currently available.

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Send completion request with negative n_discard parameter
Delivery
Parse JSON input without validation
Exploit
Trigger reversed range in llama_memory_seq_rm
Execution
Write out-of-bounds memory in token loop
Impact
Crash process or execute arbitrary code

Vulnerability AssessmentAI

Exploitation llama.cpp server with completion endpoints enabled. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment CVSS 8.8 (HIGH). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario A remote attacker could exploit this vulnerability to compromise the affected system.
Remediation Monitor vendor advisories for a patch. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 7 days: Identify all affected systems running commits 55d4206c8 and and apply vendor patches promptly. …

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Threat intelligence, references, and detailed analysis are available after sign-in.

Vendor StatusVendor

SUSE

Severity: High

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CVE-2026-21869 vulnerability details – vuln.today

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