Vulnerability · Published Mar 12, 2026 · Assigned by GitHub_M
CVE-2026-27940llama.cpp has a Heap Buffer Overflow via Integer Overflow in `mem_size` Calculation — Bypass of CVE-2025-53630 Fix
High 7.8
In plain English
A high-severity heap buffer overflow in llama.cpp from ggml-org. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 8% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.
Official description
llama.cpp is an inference of several LLM models in C/C++. Prior to b8146, the gguf_init_from_file_impl() in gguf.cpp is vulnerable to an Integer overflow, leading to an undersized heap allocation. Using the subsequent fread() writes 528+ bytes of attacker-controlled data past the buffer boundary. This is a bypass of a similar bug in the same file - CVE-2025-53630, but the fix overlooked some areas. This vulnerability is fixed in b8146.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:14 | llama.cpp | 8461+dfsg-1 | DEBIAN-CVE-2026-27940 |
| Ubuntu:25.10 | llama.cpp | no fix listed | UBUNTU-CVE-2026-27940 |
| Ubuntu:26.04:LTS | llama.cpp | no fix listed | UBUNTU-CVE-2026-27940 |
| Ubuntu:26.10 | llama.cpp | no fix listed | UBUNTU-CVE-2026-27940 |
Affected products (as reported)
Weakness: CWE-122, CWE-190 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
References
- https://github.com/ggml-org/llama.cpp/security/advisories/GHSA-3p4r-fq3f-q74v x_refsource_CONFIRM