CVE-2026-77166Network attack vector

Sidebar disruption via unvalidated page emoji

Published Sep 21, 2026 · Updated Sep 21, 2026

Improper input validation in Nextcloud Collectives 3.2.1 through 3.5.0 allows remote authenticated users to disrupt the page sidebar. PageService persists the emoji value without rejecting controls, multiple graphemes, non-emoji text, or overlong values. A user with page-edit permission can store long text and line breaks that break the sidebar layout and hide other items.

CVSS severityUnavailable
Unscored
EPSS probability0.28%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Nextcloud Collectives 3.2.1 through 3.5.0 allows remote authenticated users to disrupt the page sidebar. PageService persists the emoji value without rejecting controls, multiple graphemes, non-emoji text, or overlong values. A user with page-edit permission can store long text and line breaks that break the sidebar layout and hide other items.

The record

CVE
CVE-2026-77166
Published
Sep 21, 2026
Updated
Sep 21, 2026
Vendor
Nextcloud GmbH
Product
Collectives
Classifications
CWE-840, T1491.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 21, 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=3.2.1 <=3.5.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nextcloud GmbH · Collectivesversion=3.2.1 <=3.5.0

Published CVSS scores

No CVSS assessment is available in this record.

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.

Activity data is delayed. The latest report is Sep 28, 2026.

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

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-840Business Logic Errors
T1491.001Internal Defacement

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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