Docmost: Broken access control in transclusion lookup API leaks sync-block content across private spaces

published 2026-09-24 45 d ago modified 2026-09-29 41 d ago also EUVD-2026-86387

cvss: 4.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 8%
public exploits: 0; none known

Docmost is open-source collaborative wiki and documentation software. Prior to 0.90.1, an authenticated workspace member who does not belong to a private space can call the transclusion / sync-block lookup API with a known sourcePageId and transclusionId pair because the lookup does not enforce private space membership before resolving the source page. The API can return confidential sync-block content and source page metadata even though the normal page APIs deny access to the same page. This issue is fixed in version 0.90.1.

Patch / fix

links 2

github.com/docmost/docmost@830b5b4 commit
github.com/docmost/docmost/releases/tag/v0.90.1 release

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 41 d ago (2026-09-29)

Exploit prediction

0.19% chance of exploitation in the next 30 days, higher than 8% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	4.3	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Affected products

docmost docmost

Classification

Weakness

CWE-639 Authorization Bypass Through User-Controlled Key
CWE-862 Missing Authorization

References

Sources

CVE List CVE-2026-52850
NVD CVE-2026-52850

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary