# CVE-2026-110598: libyal libpff integer underflow in record entry parsing

Source: https://junglewise.ai/threats/cve-2026-110598-libyal-libpff-through-20260926-contains-an-integer-underflow-in  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-14. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-110598 · Severity: medium · CVSS 6.1 · Published 2026-10-14

libpff is a library for reading Outlook PST, OST, and PAB email files. An integer underflow flaw in the multi-value record parsing allows attackers to craft malicious files that trigger out-of-bounds heap reads, potentially crashing the application or exposing sensitive data from adjacent memory.

Technologies: [Libyal Libpff](https://junglewise.ai/threats/technologies/libpff). Vendors: [Libyal](https://junglewise.ai/threats/vendors/libyal).

## Quick answers

**Is CVE-2026-110598 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-110598 being exploited in the wild.

**How severe is CVE-2026-110598?** Medium severity, with a CVSS score of 6.1, published 14 October 2026.

**Which products and versions are affected?** Libyal Libpff through 20260926.

**Is there a fix for CVE-2026-110598?** 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-2026-110598 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-110598?** Check whether you run Libyal Libpff 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

An integer underflow in libpff_record_entry_get_multi_value() occurs when processing multi-value property offsets (PT_MV_STRING8, PT_MV_UNICODE, or PT_MV_BINARY types) in crafted PST/OST/PAB files. Attackers can create files with non-monotonic (decreasing) offsets to trigger out-of-bounds reads on the heap. The vulnerability requires opening a malicious file and does not require authentication or network access.

## Affected products

- libyal libpff through 20260926

## Timeline

- 2026-10-14: disclosed

## References

- [https://github.com/libyal/libpff/blob/03545511ab7a7a609e50ec715bdd3985c3be71c5/libpff/libpff_multi_value.c](https://github.com/libyal/libpff/blob/03545511ab7a7a609e50ec715bdd3985c3be71c5/libpff/libpff_multi_value.c)
- [https://github.com/libyal/libpff/blob/03545511ab7a7a609e50ec715bdd3985c3be71c5/libpff/libpff_record_entry.c](https://github.com/libyal/libpff/blob/03545511ab7a7a609e50ec715bdd3985c3be71c5/libpff/libpff_record_entry.c)

## Related threats

- [Libpff heap out-of-bounds read in table parsing](https://junglewise.ai/threats/cve-2026-116736-libpff-through-20260926-contains-a-heap-out-of-bounds-read)
- [libpff off-by-one heap buffer read in table record parsing](https://junglewise.ai/threats/cve-2026-116735-libpff-through-20260926-contains-an-off-by-one-bounds-check-in)