VulnerabilityPublished 11 Nov 2026

CVE-2026-126565: SemanticMediaWiki · Inefficient Algorithmic Complexity

Affects SemanticMediaWikiSource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium : upgrade to 7.4.1 when convenient.

Data as of 11 Nov 2026, 02:49 UTC

CVSS 4.0 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (VulnCheck)	CVSS 4.0	5.3
CNA (VulnCheck)	CVSS 3.1	4.3

Patch: Available – fixed in 7.4.1

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 11 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade SemanticMediaWiki to 7.4.1.

Affected software

Product	Affected	Fixed in
SemanticMediaWikiSemanticMediaWiki	Affected >=3.0.0 <7.4.1	Fixed in 7.4.1
PackagistSemanticMediaWiki`pkg:composer/SemanticMediaWiki`Other threats	Affected >=3.0.0 <7.4.1	Fixed in 7.4.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade Semantic MediaWiki to version 7.4.1 or later, where this vulnerability is fixed. No other mitigation or workaround is indicated.

Description

Semantic MediaWiki versions from 3.0.0 up to but not including 7.4.1 contain a denial of service vulnerability due to inefficient algorithmic complexity in certain classes. This flaw allows users with page-edit rights to create acyclic chains of Concept: pages that cause excessive CPU and memory consumption when queried, leading to service disruption. The vulnerability is fixed in version 7.4.1.

Impact

Exploitation of this vulnerability can lead to denial of service by exhausting CPU and memory resources on the affected Semantic MediaWiki instance. Attackers require page-edit rights to build the malicious concept chains that trigger the resource exhaustion. There is no indication of privilege escalation or data breach. No known exploits are reported in the wild.

Summary

CVE-2026-126565 is a denial of service vulnerability in Semantic MediaWiki affecting versions >=3.0.0 and <7.4.1. The issue resides in the ElasticStore and SPARQLStore ConceptDescriptionInterpreter classes, which re-expand concepts without memoization or an expansion budget. This inefficiency allows users with page-edit rights to construct acyclic chains of Concept: pages that fan out, causing queries via concept page views, Special:Ask, or the api.php action=ask to exhaust CPU and memory resources, resulting in denial of service conditions. The vulnerability has a CVSS 4.0 base score of 5.3 (medium severity) and was fixed in version 7.4.1.

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Affected software

Description

AI analysisMachine-generated, updated 11 Nov 2026, 02:49 UTC

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