---
id: "CVE-2026-112300"
kind: "vulnerability"
aliases: ["CVE-2026-112300"]
title: "configobj: regex in _sectionmarker can be slowed to cause denial of service"
severity: "medium"
cvss: 6.9
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["configobj", "package", "python"]
not_affected_if: ["no-untrusted-parsing", "trusted-input-only"]
published_at: "2026-10-19T21:17:06+00:00"
first_seen_at: "2026-10-23T21:57:19+00:00"
updated_at: "2026-10-25T03:40:41+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-112300", "first_seen_at": "2026-10-23T21:57:19+00:00"}]
---

# configobj: regex in _sectionmarker can be slowed to cause denial of service

configobj up to 5.0.9 has a regular expression in its _sectionmarker function with inefficient complexity. A crafted config input can make parsing consume excessive CPU, which can stall the application.

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

## How to check

- `pip show configobj` to see the installed version
- Check whether the application parses untrusted input with configobj

## Timeline

- 2026-10-23T21:57:19+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-112300

## From the sources

A vulnerability was identified in DiffSK configobj up to 5.0.9. Affected by this vulnerability is the function _sectionmarker of the file configobj/__init__.py. The manipulation leads to inefficient regular expression complexity. Remote exploitation of the attack is possible. The project was informed of the problem early through an issue report but has not responded yet.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_