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Description

A flaw has been found in ggml-org llama.cpp up to 55abc39. Impacted is the function llama_grammar_advance_stack of the file llama.cpp/src/llama-grammar.cpp of the component GBNF Grammar Handler. This manipulation causes stack-based buffer overflow. The attack needs to be launched locally. The exploit has been published and may be used. Patch name: 18993. To fix this issue, it is recommended to deploy a patch.

PUBLISHED Reserved 2026-02-06 | Published 2026-02-06 | Updated 2026-02-06 | Assigner VulDB




MEDIUM: 4.8CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
LOW: 3.3CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
LOW: 3.3CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
1.7AV:L/AC:L/Au:S/C:N/I:N/A:P/E:POC/RL:OF/RC:C

Problem types

Stack-based Buffer Overflow

Memory Corruption

Product status

55abc39
affected

Timeline

2026-02-06:Advisory disclosed
2026-02-06:VulDB entry created
2026-02-06:VulDB entry last update

Credits

TYGLS (VulDB User) reporter

References

vuldb.com/?id.344636 (VDB-344636 | ggml-org llama.cpp GBNF Grammar llama-grammar.cpp llama_grammar_advance_stack stack-based overflow) vdb-entry technical-description

vuldb.com/?ctiid.344636 (VDB-344636 | CTI Indicators (IOB, IOC, IOA)) signature permissions-required

vuldb.com/?submit.745263 (Submit #745263 | llama.cpp commit 55abc39 Stack-based Buffer Overflow) third-party-advisory

github.com/ggml-org/llama.cpp/issues/18988 issue-tracking

github.com/ggml-org/llama.cpp/issues/18988 issue-tracking

github.com/user-attachments/files/24761101/poc.zip exploit

github.com/ggml-org/llama.cpp/pull/18993 issue-tracking patch

github.com/ggml-org/llama.cpp/ product

cve.org (CVE-2026-2069)

nvd.nist.gov (CVE-2026-2069)

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