---
id: "CVE-2025-71450"
kind: "vulnerability"
aliases: ["CVE-2025-71450"]
title: "inih: one-byte stack under-read in INI parser via embedded NUL"
severity: "medium"
cvss: 4.8
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["c", "embedded", "inih", "package"]
not_affected_if: ["inih-r63-or-later", "trusted-input-only"]
published_at: "2026-11-02T15:17:12+00:00"
first_seen_at: "2026-11-02T15:24:01+00:00"
updated_at: "2026-11-02T15:26:31+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-71450", "first_seen_at": "2026-11-02T15:24:01+00:00"}]
---

# inih: one-byte stack under-read in INI parser via embedded NUL

inih is a small C library that parses INI configuration files. Before r63, a crafted line of near-maximum length followed by a NUL byte makes ini_parse_stream() read one byte before a stack buffer, which memory sanitizers flag as undefined behavior.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Find inih in your build: check the vendored copy or package version against the fixed release `r63`.
- Look for calls to `ini_parse_stream()` or `ini_parse_string()` that feed untrusted INI input.

## Fix

- Upgrade inih to `r63` or later (per the linked patch and release notes).

## Timeline

- 2026-11-02T15:24:01+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2025-71450

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/inih-before-r63-stack-buffer-under-read-in-ini-parse-stream-discard-loop
- [fix] Patch: github.com https://github.com/benhoyt/inih/commit/8e06f6b77b5d4471bdc6d85ada81b67d37354a5c
- [fix] Release notes: github.com https://github.com/benhoyt/inih/releases/tag/r63

## From the sources

inih before r63 contains a one-byte stack buffer under-read in ini_parse_stream() in ini.c that allows attackers to read abyss[-1] via an embedded NUL byte after an overlong line. Attackers can supply an INI file or string with a line of at least INI_MAX_LINE-1 bytes followed by a NUL byte, causing undefined behavior reported by memory sanitizers.

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