CVE-2026-55246 bincookie: Heap buffer overflow via unvalidated `num_pages` when parsing a `.binarycookies` file
A heap buffer overflow in the bincookie library allows attackers to cause crashes or potentially execute code by supplying a malicious .binarycookies file.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-55246?
CVE-2026-55246 is a high-severity memory corruption vulnerability in Tatsh bincookie, published on 15 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
bincookie is a header-only binarycookies parser. Prior to 0.1.9, bincookie_init_file() in bincookie.h allocates a buffer using the actual .binarycookies file length but trusts the file-controlled num_pages field as the loop bound for byte-swapping page_sizes entries. A crafted file can make the loop read and write beyond the heap allocation, and related unvalidated page sizes and cookie_offsets can drive additional out-of-bounds accesses in page and cookie iteration. Applications that parse an attacker-supplied binarycookies file may crash or suffer heap corruption that can potentially enable code execution. This issue is fixed in version 0.1.9.
Which versions are affected by CVE-2026-55246?
How do I fix CVE-2026-55246?
No fix has been published for CVE-2026-55246 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-55246 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55246 exists.
Sources
Also known as GHSA-22pc-xxw4-q849.