Global Buffer Overflow in GNU Gzip LZH Decompression
CVE-2026-41992

6.9MEDIUM

Key Information:

Vendor

Gnu
Status
Gzip
Vendor
CVE Published:
29 June 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-41992?

GNU gzip suffers from a global buffer overflow vulnerability in its LZH decompression logic. This vulnerability arises due to the improper reuse of a shared global state across different decompression formats within a single execution instance. Specifically, when decompressing a specially crafted LZW file followed by a carefully constructed LZH file using a single 'gzip -d' command, an attacker can manipulate the shared global state, triggering an out-of-bounds read during the LZH decompression process. This flaw results from the LZH logic utilizing stale values retained in the global array, which can lead to undesirable behavior and potential data leakage.

Affected Version(s)

gzip 0 <= 1.14

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-41992-poc
Created by uday952

References

https://cert.pl/en/posts/2026/04/CVE-2026-41991/
third-party-advisory
https://www.gnu.org/software/gzip/
product
https://cgit.git.savannah.gnu.org/cgit/gzip.git/commit/?i...
patch

CVSS V4

Score:
6.9
Severity:
MEDIUM
Confidentiality:
High
Integrity:
None
Availability:
None
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Michał Majchrowicz (AFINE)
Marcin Wyczechowski (AFINE)
.