# CVE-2026-116743: libyal libmsiecf double free in URL values parser

Source: https://junglewise.ai/threats/cve-2026-116743-libyal-libmsiecf-through-20260525-contains-a-double-free  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-26. Updated: 2026-10-26  
License: CC BY 4.0 with a link back

CVE-2026-116743 · Severity: medium · CVSS 5.5 · Published 2026-10-26

libmsiecf is a library that reads Microsoft Internet Explorer cache files (index.dat) used by forensic analysts and security tools. A double-free vulnerability in the URL parsing code allows an attacker to crash these tools or corrupt memory by providing a malicious cache file with oversized offset values in partial URL records.

Vendors: [Libyal](https://junglewise.ai/threats/vendors/libyal).

## Quick answers

**Is CVE-2026-116743 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-116743 being exploited in the wild.

**How severe is CVE-2026-116743?** Medium severity, with a CVSS score of 5.5, published 26 October 2026.

**Which products and versions are affected?** Libyal Libmsiecf through 20260525.

**Is there a fix for CVE-2026-116743?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-116743 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-116743?** Check whether you run Libyal Libmsiecf at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A double-free vulnerability exists in the libmsiecf_url_values_read_data() function that processes partial URL records from MSIE cache index.dat files. An attacker can craft a malicious cache file with an oversized unknown_offset field that triggers the double-free condition, leading to heap memory corruption. This vulnerability requires the victim to process a crafted index.dat file, resulting in denial of service to forensic tools.

## Affected products

- libyal libmsiecf through 20260525

## Timeline

- 2026-10-26: disclosed

## References

- [https://github.com/libyal/libmsiecf](https://github.com/libyal/libmsiecf)
- [https://github.com/libyal/libmsiecf/blob/20260525/libmsiecf/libmsiecf_url_values.c](https://github.com/libyal/libmsiecf/blob/20260525/libmsiecf/libmsiecf_url_values.c)