CVE-2026-111138: Out-of-bounds Read (CVSS 5.5)

Description

NetSurf libnsbmp through 0.1.7 contains an out-of-bounds read vulnerability in bmp_decode_rle8() and bmp_decode_rle4() because absolute-run bound checks omit the word-alignment pad byte. Attackers can supply a crafted RLE8 or RLE4 BMP ending on an odd-length absolute run to cause a one-byte heap over-read, crashing applications decoding untrusted images.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-125 Out-of-bounds Read

References

Other References

https://download.netsurf-browser.org/libs/releases/libnsbmp-0.1.7-src.tar.gz https://github.com/netsurf-browser/libnsbmp https://github.com/netsurf-browser/libnsbmp/blob/ea063c9f46acb43e90208da14073332b505ef7e7/src/libnsbmp.c#L1096-L1147 https://github.com/netsurf-browser/libnsbmp/blob/ea063c9f46acb43e90208da14073332b505ef7e7/src/libnsbmp.c#L942-L982 https://hackmd.io/@haind-pwn/libnsbmp-rle-absolute-pad-and-ico-mask-oob-read https://www.vulncheck.com/advisories/netsurf-libnsbmp-through-0.1.7-out-of-bounds-read-in-rle8-and-rle4-decoders

Frequently Asked Questions

What is CVE-2026-111138? +

NetSurf libnsbmp through 0.1.7 contains an out-of-bounds read vulnerability in bmp_decode_rle8() and bmp_decode_rle4() because absolute-run bound checks omit the word-alignment pad byte. Attackers can supply a crafted RLE8 or RLE4 BMP ending on an odd-length absolute run to cause a one-byte heap over-read, crashing applications decoding untrusted images. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2026-111138? +

CVE-2026-111138 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

How do I check if I'm vulnerable to CVE-2026-111138? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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