CVE-2026-41992: GNU gzip contains a global buffer overflow vulnerability in the LZH decompression logic caused by improper reuse of shared global state between different decomp

GNU gzip contains a global buffer overflow vulnerability in the LZH decompression logic caused by improper reuse of shared global state between different decomp

GNU gzip contains a global buffer overflow vulnerability in the LZH decompression logic caused by improper reuse of shared global state between different decompression formats within a single execution. GNU gzip maintains a global array that is shared across the LZ77, LZW, and LZH decompression routines and is not reinitialized between files processed in the same invocation. By decompressing a specially crafted LZW file followed by a specially crafted LZH file in a single gzip -d command, an attacker can poison the shared global state and subsequently trigger an out‑of‑bounds read in the LZH decoder. The LZH decompression logic follows stale values left in the shared array, causing reads past the end of the allocated global buffer. This issue has been fixed in commits 63dbf6b3b9e6e781df1a6a64e609b10e23969681 and e7378c2d421be6a286922374425680bbe9ad8b7d.

Description from the National Vulnerability Database, published by cvd@cert.pl

What it means for a small business

If your business uses gzip, install the vendor's update. If you're not sure whether you use it, ask whoever manages your computers.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.62%, higher than 49% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 28, 2026, updated daily.

Check your own setup

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Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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