CVE-2026-45282Network attack vector

Authenticated attachment disclosure via skipped share-token validation

Published Jun 1, 2026 · Updated Jun 1, 2026

Improper access control in Nextcloud Server 32.0.0 through 32.0.8 and 33.0.0 through 33.0.2 allows remote authenticated users to read attachments. Text app's SessionMiddleware.assertUserOrShareToken returned early when a logged-in user's documentId resolved in that user's files, so a supplied shareToken was never validated. Exploitation requires an account and the share token; direct-file shares accept an attacker-owned documentId, while folder shares require a contained file's documentId, and only attachments are exposed.

CVSS severity6.5
Medium
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Nextcloud Server 32.0.0 through 32.0.8 and 33.0.0 through 33.0.2 allows remote authenticated users to read attachments. Text app's SessionMiddleware.assertUserOrShareToken returned early when a logged-in user's documentId resolved in that user's files, so a supplied shareToken was never validated. Exploitation requires an account and the share token; direct-file shares accept an attacker-owned documentId, while folder shares require a contained file's documentId, and only attachments are exposed.

The record

CVE
CVE-2026-45282
Published
Jun 1, 2026
Updated
Jun 1, 2026
Vendor
Nextcloud GmbH
Product
Nextcloud Security Advisories
Classifications
CWE-284, T1530
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 1, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 1, 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=>= 32.0.0, < 32.0.9
  2. Affected versionversion=>= 33.0.0, < 33.0.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nextcloud GmbH · Nextcloud Security Advisoriesversion=>= 32.0.0, < 32.0.9; version=>= 33.0.0, < 33.0.3

Published CVSS scores

6.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control
T1530Data from Cloud Storage

Public exploit references

No public exploit references are available in this record.

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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