# CVE-2026-112300: DiffSK configobj __init__.py _sectionmarker redos

> Attackers can cause denial of service in DiffSK configobj via inefficient regular expression complexity in the section marker parser.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 19 Oct 2026
- **Updated:** 20 Oct 2026
- **Also known as:** AZL-110064, BELL-CVE-2026-112300, DEBIAN-CVE-2026-112300, GHSA-w53r-mv8r-wgxx, UBUNTU-CVE-2026-112300

## What is CVE-2026-112300?

CVE-2026-112300 is a medium-severity denial of service vulnerability in DiffSK configobj, published on 19 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-400 (Uncontrolled Resource Consumption), CWE-1333 (Inefficient Regular Expression Complexity)

## Which versions are affected by CVE-2026-112300?


## How do I fix CVE-2026-112300?

No fix has been published for CVE-2026-112300 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-112300 being exploited?

There is no known exploitation of CVE-2026-112300 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-112300 and fix it if it is affected.

What it is: CVE-2026-112300 is a medium-severity denial of service vulnerability in DiffSK configobj, published on 19 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-112300 in the wild and no public exploit code.

Affected product: DiffSK configobj. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-112300/ (Markdown: https://insights.sbomify.com/CVE-2026-112300/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-112300
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-112300
- OSV: https://osv.dev/vulnerability/CVE-2026-112300

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-112300/
Summaries are generated and may contain mistakes; the official description above is the record.