bincookie: Heap buffer overflow when parsing crafted binarycookies files
Summary
The header-only C library bincookie, which parses Apple binarycookies files, trusts file-controlled fields such as num_pages, page sizes and cookie offsets without bounds checks. An attacker who supplies a crafted .binarycookies file can cause reads and writes beyond the heap allocation. This may crash the application or corrupt heap memory, which could potentially lead to code execution.
Affected
- bincookie versions before 0.1.9
Fixed in
- Fixed in bincookie 0.1.9 (commit bc1433c1ee4d0284750ff85c8437f1b8df91ab3b)
Workaround
- Unknown. No vendor-documented workaround exists.
- Parse only trusted cookie files and run the parsing step in an isolated process or sandbox as an interim measure.
Exploitation
- No confirmed exploitation in the wild known; CISA KEV lists the CVE as not included.
- CISA SSVC assessment lists exploitation as PoC, automatable as no, technical impact as total.
Our recommendation
- Identify whether any software in your environment bundles or uses bincookie, for example via software inventories or SBOMs.
- Upgrade bincookie to version 0.1.9 or later.
- Until upgraded, only process binarycookies files from trusted sources.
- Re-check the CISA KEV catalog and the NVD analysis, which is currently deferred.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- GitHub Security Advisory GHSA-22pc-xxw4-q849 github.com
- bincookie v0.1.9 release github.com
- Fix commit bc1433c github.com
- CVE record mirror (Vulners CVELIST) vulners.com
- OpenCVE CVE-2026-55246 app.opencve.io
- bincookie repository github.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 23:55.
Original description (NVD)
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.
NVD references (4)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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