CVE-2026-100240VulnerabilityPublished 29 Sep 2026Updated 1 Oct 2026

Wikimedia Foundation Mediawiki - TemplateSandbox Extension · Missing Authorization Vulnerability

Source GCVE Database

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Authoritative record:CVE-2026-100240· Critical 9.1

Not known to be exploited · CVSS 9.1 Critical : upgrade to 1.46.1 as a priority.

Data as of 13 Nov 2026, 23:53 UTC

CVSS 3.1 base score

9.1Critical

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.46.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: None

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, 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: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 29 Sep 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 14 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.

ghsa-3835-4xp5-hjqc

What to do

Upgrade Mediawiki – TemplateSandbox Extension to 1.46.1.

Affected software

Product	Affected	Fixed in
Wikimedia FoundationMediawiki - TemplateSandbox Extension	Affected < 1.46.1, 1.45.5, 1.43.10	Fixed in 1.46.1

AI-suggested

No explicit patch or remediation link is provided in the available data. If you cannot patch yet, restrict access to the affected TemplateSandbox Extension versions or disable the extension if feasible.

Description

CVE-2026-100240 is a critical missing authorization vulnerability in the Wikimedia Foundation's Mediawiki TemplateSandbox Extension. It allows unauthorized access to functionality that is not properly constrained by access control lists (ACLs). The vulnerability affects multiple versions of the TemplateSandbox Extension prior to 1.46.1, including specific ranges 1.43.0 to before 1.43.10 and 1.45.0 to before 1.45.5.

Impact

Exploitation of this vulnerability could allow unauthenticated attackers to access sensitive functionality that should be restricted, potentially leading to unauthorized disclosure and modification of information. The vulnerability does not impact availability. Given the high CVSS score and the nature of missing authorization, the impact is critical.

Summary

This vulnerability (CWE-862) in the Mediawiki TemplateSandbox Extension arises from missing authorization checks, enabling attackers to access functionality without proper ACL enforcement. It affects all versions before 1.46.1, including 1.43.0 through 1.43.9 and 1.45.0 through 1.45.4. The CVSS v3.1 score is 9.1, indicating a critical severity with network attack vector, no privileges required, no user interaction, and high impact on confidentiality and integrity.

CWE-862Missing Authorization (opens in a new tab)
Class weaknessLikelihood of exploit: HighCWE Top 25 (2025): #4OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product does not perform an authorization check when an actor attempts to access a resource or perform an action.
Architecture and Design
Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) to enforce the roles at the appropriate boundaries.
Architecture and Design
Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.8 (opens in a new tab)
V13.4.2 (opens in a new tab)
V7.2.2 (opens in a new tab)
Attack patterns
Exploitation of Thunderbolt Protection Flaws (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 7 Oct 2026, 19:02 UTC

WeaknessesCWE-862

Technical details

References

Community reviews

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