CVE-2026-0668VulnerabilityPublished 7 Jan 2026

CVE-2026-0668: Wikimedia Foundation MediaWiki – VisualData Extension · ReDoS

Affects Wikimedia Foundation MediaWiki – VisualData ExtensionSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

5.3Medium

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 40% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
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 impacted component 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 impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 7 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 2026-10-25.

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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC 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

Affected software

Product	Affected	Fixed in
Wikimedia FoundationMediaWiki - VisualData Extension	Affected =1.45	Fixed in–

AI-suggested

To mitigate CVE-2026-0668, European organizations should: 1) Immediately assess if MediaWiki installations are running version 1.45 with the VisualData extension enabled. 2) Disable the VisualData extension temporarily if it is not critical to operations until a patch or update is available. 3) Monitor official Wikimedia Foundation channels for patches or updates addressing this vulnerability and apply them promptly once released. 4) Implement web application firewalls (WAFs) with rules to detect and block suspicious input patterns that could trigger regex blowup. 5) Limit exposure by restricting access to MediaWiki instances to trusted networks or VPNs where feasible. 6) Conduct regular performance monitoring and alerting on MediaWiki servers to detect unusual CPU or memory usage indicative of ReDoS attempts. 7) Review and optimize any custom regex patterns in MediaWiki extensions or templates to prevent similar inefficiencies. 8) Educate administrators and developers about the risks of inefficient regex usage and best practices for secure coding. These targeted actions go beyond generic advice by focusing on immediate risk reduction and proactive detection tailored to this specific vulnerability.

Description

CVE-2026-0668 is a medium-severity vulnerability in the Wikimedia Foundation's MediaWiki VisualData Extension version 1.45. It involves inefficient regular expression complexity, leading to a potential Regular Expression Denial of Service (ReDoS) attack. This vulnerability can be exploited remotely without authentication or user interaction, causing service disruption by exhausting server resources. No known exploits are currently reported in the wild. The impact is limited to availability, with no confidentiality or integrity compromise. European organizations running affected MediaWiki versions with the VisualData extension are at risk of service degradation or downtime. Mitigation requires patching or applying workarounds to limit or optimize regex processing. Countries with significant Wikimedia usage and MediaWiki deployments, such as Germany, France, and the UK, are most likely affected. The vulnerability's CVSS score is 5.

Impact

For European organizations, the primary impact of CVE-2026-0668 is the potential denial of service caused by resource exhaustion on servers running MediaWiki with the VisualData extension version 1.45. This can lead to downtime or degraded performance of internal or public-facing wiki services, affecting knowledge sharing, documentation, and collaboration workflows. Organizations relying heavily on MediaWiki for critical information management may experience operational disruptions. Although the vulnerability does not compromise data confidentiality or integrity, availability issues can indirectly affect business continuity and user trust. The lack of authentication requirements means attackers can exploit this remotely, increasing the risk of widespread attacks. Given the open-source nature of MediaWiki and its adoption in various public and private sectors across Europe, the threat is relevant to governmental, educational, and corporate entities. The absence of known exploits in the wild reduces immediate risk but does not eliminate the potential for future attacks, especially if the vulnerability becomes publicly known and weaponized.

CWE-1333Inefficient Regular Expression Complexity (opens in a new tab)
Base weaknessLikelihood of exploit: High
The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.
Architecture and Design
Use regular expressions that do not support backtracking, e.g. by removing nested quantifiers.
System Configuration
Set backtracking limits in the configuration of the regular expression implementation, such as PHP's pcre.backtrack_limit. Also consider limits on execution time for the process.
Implementation
Do not use regular expressions with untrusted input. If regular expressions must be used, avoid using backtracking in the expression.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
Attack patterns
Regular Expression Exponential Blowup (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 14 Jan 2026, 19:46 UTC

WeaknessesCWE-1333

Technical details

References

Community reviews

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