# CVE-2026-105842: lrzsz heap buffer overflow in procheader

Source: https://junglewise.ai/threats/cve-2026-105842-lrzsz-before-0-13-0-contains-a-heap-based-buffer-overflow  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-06. Updated: 2026-10-06  
License: CC BY 4.0 with a link back

CVE-2026-105842 · Severity: medium · CVSS 6.4 · Published 2026-10-06

lrzsz is a Unix utility for transferring files using XMODEM, YMODEM, and ZMODEM protocols. A heap buffer overflow in the lrz receive utility can be triggered when a malicious sender supplies overlong filenames during ZMODEM file transfers, allowing an attacker to crash the program or potentially execute arbitrary code.

Technologies: [Uwe Ohse Lrzsz](https://junglewise.ai/threats/technologies/lrzsz). Vendors: [Uwe Ohse](https://junglewise.ai/threats/vendors/uwe-ohse).

## Quick answers

**Is CVE-2026-105842 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-105842 being exploited in the wild.

**How severe is CVE-2026-105842?** Medium severity, with a CVSS score of 6.4, published 6 October 2026.

**Which products and versions are affected?** Uwe Ohse Lrzsz before 0.13.0.

**Is there a fix for CVE-2026-105842?** Yes: fixed in lrzsz 0.13.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-105842 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-105842?** Check whether you run Uwe Ohse Lrzsz 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.

## How to fix

- Fixed in lrzsz 0.13.0

## Technical details

The procheader() function in lrz copies sender-supplied filenames into a fixed-size Pathname buffer without proper length validation, allowing filenames up to 8192 bytes to overflow the heap via sprintf() in pipe mode or strcpy(). The vulnerability requires a ZMODEM file transfer initiated by a malicious sender and can result in heap memory corruption, denial of service, or potential code execution.

## Affected products

- Uwe Ohse lrzsz before 0.13.0

## Timeline

- 2026-10-06: disclosed
- 2026-09: patched: version 0.13.0 released

## References

- [https://ohse.de/uwe/software/lrzsz.html](https://ohse.de/uwe/software/lrzsz.html)
- [https://ohse.de/uwe/software/lrzsz/NEWS-0.13.0.html](https://ohse.de/uwe/software/lrzsz/NEWS-0.13.0.html)

## Related threats

- [lrzsz OS command injection in lrz pipe mode](https://junglewise.ai/threats/cve-2026-105841-lrzsz-before-0-13-0-contains-an-os-command-injection)
- [lrzsz path traversal in lrz restricted mode](https://junglewise.ai/threats/cve-2026-105840-lrzsz-before-0-13-0-contains-a-path-traversal-vulnerability-in)