CVE-2026-34213Public exploitNetwork attack vector

Cross-page attachment overwrite via mismatched object authorization

Published Apr 14, 2026 · Updated Apr 14, 2026

Improper authorization in Docmost 0.3.0 through 0.70.3 allows remote authenticated users to overwrite attachments on other pages. The POST /api/files/upload handler authorizes the supplied pageId but accepts a separate victim attachmentId, so its flawed overwrite guard rebuilds the storage path for the victim file. Low-privileged edit access to one page in the same workspace is sufficient, and no victim interaction is required.

CVSS severity7.1
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authorization in Docmost 0.3.0 through 0.70.3 allows remote authenticated users to overwrite attachments on other pages. The POST /api/files/upload handler authorizes the supplied pageId but accepts a separate victim attachmentId, so its flawed overwrite guard rebuilds the storage path for the victim file. Low-privileged edit access to one page in the same workspace is sufficient, and no victim interaction is required.

The record

CVE
CVE-2026-34213
Published
Apr 14, 2026
Updated
Apr 14, 2026
Vendor
Docmost
Product
Docmost
Classifications
CWE-639, T1565.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 0.3.0, < 0.71.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Docmost · Docmostversion=>= 0.3.0, < 0.71.0

Published CVSS scores

7.1GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-639Authorization Bypass Through User-Controlled Key
T1565.001Stored Data Manipulation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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