# CVE-2026-100377: MediaWiki WikiLambda information disclosure in revision handling

Source: https://junglewise.ai/threats/cve-2026-100377-exposure-of-sensitive-information-to-an-unauthorized-actor  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-25. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-100377 · Severity: info · Published 2026-09-25

WikiLambda, an extension for the MediaWiki wiki platform, fails to properly check access permissions when displaying page revisions that administrators have marked as deleted. An attacker can bypass these deletion restrictions by using the edit action parameter or the ViewAbstract page to view content that should be hidden, potentially exposing sensitive information like suppressed personal data or private discussions.

Technologies: [Wikimedia Foundation Mediawiki WikiLambda extension](https://junglewise.ai/threats/technologies/mediawiki-wikilambda-extension). Vendors: [Wikimedia Foundation](https://junglewise.ai/threats/vendors/wikimedia-foundation).

## Quick answers

**Is CVE-2026-100377 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-100377 being exploited in the wild.

**How severe is CVE-2026-100377?** Informational severity, published 25 September 2026.

**Which products and versions are affected?** Wikimedia Foundation Mediawiki WikiLambda extension 1.47.0-alpha.

**Is there a fix for CVE-2026-100377?** A patch was published on 2026-07-30: Fix committed to master branch in Gerrit Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-100377 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-100377?** Check whether you run Wikimedia Foundation Mediawiki WikiLambda extension at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in SpecialViewAbstract.php and AbstractWikiContentHandler.php, which call RevisionRecord::getMainContentRaw() to bypass standard permission checks. The code fails to verify that a revision has not been deleted or suppressed before serving its contents to users. An unauthenticated attacker can append ?action=edit or navigate to Special:ViewAbstract with an oldid parameter pointing to a deleted revision to retrieve the concealed content.

## Affected products

- Wikimedia Foundation MediaWiki WikiLambda Extension 1.47.0-alpha

## Timeline

- 2026-06-29: disclosed
- 2026-07-30: patched: Fix committed to master branch in Gerrit

## References

- [https://gerrit.wikimedia.org/r/c/mediawiki/extensions/WikiLambda/+/1320186](https://gerrit.wikimedia.org/r/c/mediawiki/extensions/WikiLambda/+/1320186)
- [https://phabricator.wikimedia.org/T430601](https://phabricator.wikimedia.org/T430601)

## Related threats

- [Wikimedia MediaWiki WikiLambda stored cross-site scripting](https://junglewise.ai/threats/cve-2026-103046-improper-neutralization-of-input-during-web-page-generation)
- [Mediawiki WikiLambda extension stored XSS in Visual Editor integration](https://junglewise.ai/threats/cve-2026-100383-improper-neutralization-of-input-during-web-page-generation-xss)
- [Wikimedia MediaWiki WikiLambda privilege escalation](https://junglewise.ai/threats/cve-2026-96872-improper-handling-of-insufficient-permissions-or-privileges)