---
id: "CVE-2026-116871"
kind: "vulnerability"
aliases: ["CVE-2026-116871"]
title: "Semantic MediaWiki: unauthenticated nested queries exhaust CPU and memory"
severity: "high"
cvss: 8.7
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["mediawiki", "package", "self-hosted", "semantic-mediawiki"]
not_affected_if: ["version-7.3.1-or-later"]
published_at: "2026-10-27T11:17:28+00:00"
first_seen_at: "2026-10-27T11:31:27+00:00"
updated_at: "2026-10-27T11:31:42+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-116871", "first_seen_at": "2026-10-27T11:31:27+00:00"}]
---

# Semantic MediaWiki: unauthenticated nested queries exhaust CPU and memory

Semantic MediaWiki 3.0.0 before 7.3.1 recurses without a depth limit when parsing nested query tokens in LegacyParser::getSubqueryDescription(). An unauthenticated attacker can send deeply nested queries to the action=ask API to consume CPU and memory and tie up request workers, causing denial of service.

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

## How to check

- Check the installed Semantic MediaWiki version in Special:Version or in composer.lock for `mediawiki/semantic-media-wiki`, and see whether it is `3.0.0` through `7.3.0`.
- Confirm whether the wiki exposes the action=ask API to anonymous users.

## Fix

- Upgrade Semantic MediaWiki to `7.3.1` or later.

## Timeline

- 2026-10-27T11:31:27+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-116871

## From the sources

Semantic MediaWiki 3.0.0 before 7.3.1 contains an uncontrolled recursion vulnerability in LegacyParser::getSubqueryDescription() that processes nested query tokens before depth limits apply. Unauthenticated attackers can submit deeply nested query elements to the action=ask API to consume substantial CPU and memory, tying up request workers.

---

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