Vulnerability · Published Oct 15, 2026 · Assigned by VulnCheck
CVE-2026-111139NetSurf libnsbmp through 0.1.7 Out-of-Bounds Read via bmp_decode_mask
Medium 5.5
In plain English
A medium-severity out-of-bounds read in libnsbmp from NetSurf. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 2% of all known vulnerabilities).
Severity (CVSS 3.1)5.5Medium
Exploit odds (30 days)0.1%top 97.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official description
NetSurf libnsbmp through 0.1.7 contains an out-of-bounds read vulnerability in bmp_decode_mask() that allows attackers to read one byte past the image buffer by supplying crafted ICO files. Attackers can provide an ICO whose inner bitmap width is not a multiple of 8, causing a heap over-read that can crash applications calling bmp_decode().
Affected products (as reported)
Weakness: CWE-125 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
References
- https://hackmd.io/@haind-pwn/libnsbmp-rle-absolute-pad-and-ico-mask-oob-read technical-description, exploit
- https://github.com/netsurf-browser/libnsbmp/blob/ea063c9f46acb43e90208da14073332b505ef7e7/src/libnsbmp.c#L835-L873 technical-description
- https://download.netsurf-browser.org/libs/releases/libnsbmp-0.1.7-src.tar.gz product
- https://github.com/netsurf-browser/libnsbmp product
- VulnCheck Advisory: NetSurf libnsbmp through 0.1.7 Out-of-Bounds Read via bmp_decode_mask third-party-advisory