Semantic MediaWiki: Denial of service via exponential concept expansion
Summary
Semantic MediaWiki 3.0.0 before 7.4.1 contains a denial of service vulnerability in the ElasticStore and SPARQLStore ConceptDescriptionInterpreter classes. Concept descriptions are re-expanded without memoization or an expansion budget. An authenticated user with page-edit rights can create chains of Concept: pages that fan out, so that queries via concept page views, Special:Ask or api.php action=ask exhaust CPU and memory on the wiki server.
Affected
- Semantic MediaWiki 3.0.0 up to but not including 7.4.1
- Versions before 3.0.0: Unknown.
Fixed in
- Semantic MediaWiki 7.4.1
Workaround
- No vendor workaround known.
- Limit page-edit rights to trusted accounts until 7.4.1 is installed.
- Review recently created Concept: pages for unusual chains.
Exploitation
- Not listed in the CISA KEV catalog.
- No public proof of concept or exploit code known at the time of research.
Our recommendation
- Upgrade Semantic MediaWiki to 7.4.1 or later; this release also contains the other SMW fixes published with this CVE.
- Restrict page-edit rights, especially on wikis that accept edits from many users or self-registration.
- Monitor CPU and memory usage of the wiki server and review new Concept: pages.
- Priority: medium.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- CVE record (VulnCheck advisory) www.vulncheck.com
- GitHub security advisory GHSA-24v2-mf3g-84ch github.com
- SMW release 7.4.1 github.com
- Fix commit 86ce132 github.com
- ConceptDescriptionInterpreter (ElasticStore, 7.4.0) github.com
- ConceptDescriptionInterpreter (SPARQLStore, 7.4.0) github.com
- OffSeq Radar entry CVE-2026-126565 radar.offseq.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 11 Nov 2026, 18:12.
Original description (NVD)
Semantic MediaWiki 3.0.0 before 7.4.1 contains a denial of service vulnerability in the ElasticStore and SPARQLStore ConceptDescriptionInterpreter classes, which re-expand concepts without memoization or an expansion budget. Users with page-edit rights can build acyclic chains of Concept: pages that fan out, so queries via concept page views, Special:Ask, or api.php action=ask exhaust CPU and memory.
NVD references (7)
- https://github.com/SemanticMediaWiki/SemanticMediaWiki/blob/7.4.0/src/Elastic/QueryEngine/DescriptionInterpre…
- https://github.com/SemanticMediaWiki/SemanticMediaWiki/blob/7.4.0/src/SPARQLStore/QueryEngine/DescriptionInte…
- https://github.com/SemanticMediaWiki/SemanticMediaWiki/commit/86ce13254ffd91406ef43ea403ae072a7e3a38b3
- https://github.com/SemanticMediaWiki/SemanticMediaWiki/releases/tag/7.4.1
- https://github.com/SemanticMediaWiki/SemanticMediaWiki/security/advisories/GHSA-24v2-mf3g-84ch
- https://www.vulncheck.com/advisories/semantic-mediawiki-3.0.0-before-7.4.1-dos-via-exponential-concept-expans…
- https://github.com/SemanticMediaWiki/SemanticMediaWiki/security/advisories/GHSA-24v2-mf3g-84ch
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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