---
id: CVE-2026-111139
title: >-
  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
summary: >-
  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…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'
cwe:
  - CWE-125
vendor: NetSurf
product: libnsbmp
affected:
  - libnsbmp <= 0.1.7
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T19:17:27.983'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-111139'
references:
  - url: >-
      https://download.netsurf-browser.org/libs/releases/libnsbmp-0.1.7-src.tar.gz
    label: disclosure@vulncheck.com
  - url: 'https://github.com/netsurf-browser/libnsbmp'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/netsurf-browser/libnsbmp/blob/ea063c9f46acb43e90208da14073332b505ef7e7/src/libnsbmp.c#L835-L873
    label: disclosure@vulncheck.com
  - url: >-
      https://hackmd.io/@haind-pwn/libnsbmp-rle-absolute-pad-and-ico-mask-oob-read
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/netsurf-libnsbmp-through-0.1.7-out-of-bounds-read-via-bmp-decode-mask
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-15T19:25:46.411Z'
---

## Overview

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().

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.