Nextcloud Collectives up to 3.5.0 Page Emoji Update Endpoint emoji injection

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
2.4$0-$5k1.27

Summaryinfo

A vulnerability was found in Nextcloud Collectives up to 3.5.0 and classified as problematic. This affects an unknown part of the component Page Emoji Update Endpoint. Such manipulation of the argument emoji leads to injection. This vulnerability is documented as CVE-2026-77166. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in Nextcloud Collectives up to 3.5.0 and classified as problematic. Affected by this issue is an unknown code of the component Page Emoji Update Endpoint. The manipulation of the argument emoji with an unknown input leads to a injection vulnerability. Using CWE to declare the problem leads to CWE-74. The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. Impacted is integrity. CVE summarizes:

The emoji field in the page emoji update endpoint does not properly validate user input. By injecting long text and line breaks, the sidebar layout becomes broken and can hide other items.

The advisory is available at hackerone.com. This vulnerability is handled as CVE-2026-77166 since 08/20/2026. The exploitation is known to be easy. The attack may be launched remotely. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 09/21/2026). This vulnerability is assigned to T1055 by the MITRE ATT&CK project.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 2.4
VulDB Meta Temp Score: 2.4

VulDB Base Score: 2.4
VulDB Temp Score: 2.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 2.4
CNA Vector (hackerone): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Injection
CWE: CWE-74 / CWE-707 / CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

08/20/2026 CVE reserved
09/21/2026 +32 days Advisory disclosed
09/21/2026 +0 days VulDB entry created
09/21/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: hackerone.com
Status: Not defined

CVE: CVE-2026-77166 (🔒)
GCVE (CVE): GCVE-0-2026-77166
GCVE (VulDB): GCVE-100-408146

Entryinfo

Created: 09/21/2026 17:40
Changes: 09/21/2026 17:40 (63)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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