CVE-2026-43631 llama.cpp b7492–b9060 Use-After-Free RCE via llama-server
Unauthenticated attackers can achieve remote code execution in llama-server via a use-after-free vulnerability when the sleep-idle-seconds feature is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-43631?
CVE-2026-43631 is a critical use after free vulnerability in ggml-org llama.cpp, published on 6 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
llama.cpp builds b7492 through the latest b9060 contains a use-after-free vulnerability in the vocab pointer of llama-server when the --sleep-idle-seconds feature is enabled, allowing unauthenticated remote attackers to execute arbitrary code. Attackers can trigger the vulnerability by sending requests to affected endpoints while the server transitions to sleep mode, causing concurrent worker threads to dereference a freed vocab pointer that can be reclaimed with attacker-controlled data to achieve remote code execution.
Which versions are affected by CVE-2026-43631?
It affects 1 product.
Products include Ggml Llama.cpp.
How do I fix CVE-2026-43631?
No fix has been published for CVE-2026-43631 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-43631 being exploited?
There is no known exploitation of CVE-2026-43631 in the wild and no public exploit code.
Other vulnerabilities in ggml-org llama.cpp
- CVE-2024-42479 llama.cpp allows write-what-where in rpc_server::set_tensor
- CVE-2026-34159 llama.cpp: Unauthenticated RCE via GRAPH_COMPUTE buffer=0 bypass in llama.cpp RPC backend
- CVE-2026-43629 llama.cpp b4882–b9058 Buffer Overflow in KV Cache State Restore
- CVE-2026-43632 llama.cpp b7492–b9060 Use-After-Free in Tokenization Endpoints
- CVE-2026-21869 llama.cpp has Out-of-bounds Write in llama-server
Sources
Also known as DEBIAN-CVE-2026-43631, GHSA-6hc7-9rph-cm99, UBUNTU-CVE-2026-43631.