libsmi through 0.5.0 Out-of-Bounds Write via smiValueAsString OCTET STRING DEFVAL

Advisories

libsmi through 0.5.0 Out-of-Bounds Write via smiValueAsString OCTET STRING DEFVAL

Severity: medium
Date: 10/15/2026
Affecting: libsmi <= 0.5.0
CVE: CVE-2026-111137
CWE: CWE-787 Out-of-bounds Write
CVSS: 6.9
CVSS V4 Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
References: https://hackmd.io/@haind-pwn/libsmi-smivalueasstring-octetstring-defval-oob-write
https://github.com/amartin755/libsmi/blob/c58307210fe995ec419db976eb234aebc71a9216/lib/smi.c#L479-L566
https://github.com/amartin755/libsmi
Credit: HaiND from the Post and Telecommunication Institute of Technology
Description: libsmi through 0.5.0 contains an out-of-bounds write vulnerability in smiValueAsString() in lib/smi.c that allows attackers to overflow a fixed 1024-byte static buffer through hex rendering of OCTET STRING values. Attackers can supply a crafted MIB with an OCTET STRING DEFVAL of 512 or more octets and a leading 0x00 byte to corrupt adjacent library globals and crash smidump or other consumers.

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