CVE-2026-12043 Heap double-free in AWS Common Runtime aws-c-http
A remote attacker can trigger a heap double-free in the AWS Common Runtime HTTP library via crafted HTTP/2 frames, potentially leading to arbitrary code execution on client applications.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-12043?
CVE-2026-12043 is a high-severity use after free vulnerability in aws-c-http, published on 12 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Improper handling of HPACK dynamic table size updates in the AWS Common Runtime aws-c-http library might allow a remote threat actor operating a server to cause memory corruption on a connecting client application, potentially leading to arbitrary code execution, via a crafted sequence of HTTP/2 HEADERS frames.
To remediate this issue, users should upgrade to aws-c-http version 0.11.0.
Weakness: CWE-415
Which versions are affected by CVE-2026-12043?
How do I fix CVE-2026-12043?
No fix has been published for CVE-2026-12043 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-2026-12043 being exploited?
There is no known exploitation of CVE-2026-12043 in the wild and no public exploit code.
Sources
Also known as GHSA-rmjr-3qpm-vh98.