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Online CVE-2023-31145

MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2023-05-15 security-advisories@github.com
6.1
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK

2 techniques across 2 tactics: Initial Access, Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 6.1 (MEDIUM). Attack characteristics: network attack vector, low complexity, no privileges required, user interaction required.

Exploit ScenarioDerived

A remote attacker could inject malicious scripts into web pages viewed by other users by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.4% exploitation probability (EPSS)

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AnalysisAI

Collabora Online is a collaborative online office suite based on LibreOffice technology. Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Sanitize all user input, use Content-Security-Policy headers, encode output contextually (HTML, JS, URL). Use frameworks with built-in XSS protection.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Cross-Site Scripting (XSS) (CWE-79), which allows attackers to inject malicious scripts into web pages viewed by other users. Collabora Online is a collaborative online office suite based on LibreOffice technology. This vulnerability report describes a reflected XSS vulnerability with full CSP bypass in Nextcloud installations using the recommended bundle. The vulnerability can be exploited to perform a trivial account takeover attack. The vulnerability allows attackers to inject malicious code into web pages, which can be executed in the context of the victim's browser session. This means that an attacker can steal sensitive data, such as login credentials or personal information, or perform unauthorized actions on behalf of the victim, such as modifying or deleting data. In this specific case, the vulnerability allows for a trivial account takeover attack. An attacker can exploit the vulnerability to inject code into the victim's browser session, allowing the attacker to take over the victim's account without their knowledge or consent. This can lead to unauthorized access to sensitive information and data, as well as the ability to perform actions on behalf of the victim. Furthermore, the fact that the vulnerability bypasses the Content Security Policy (CSP) makes it more dangerous, as CSP is an important security mechanism used to prevent cross-site scripting attacks. By bypassing CSP, attackers can circumvent the security measures put in place by the web application and execute their malicious code. This issue has been patched in versions 22.05.13, 21.11.9, and 6.4.27. Users are advised to upgrade. There are no known workarounds for this vulnerability. Affected products include: Collabora Online.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 6.1 MEDIUM
AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

DescriptionNVD

Collabora Online is a collaborative online office suite based on LibreOffice technology. This vulnerability report describes a reflected XSS vulnerability with full CSP bypass in Nextcloud installations using the recommended bundle. The vulnerability can be exploited to perform a trivial account takeover attack. The vulnerability allows attackers to inject malicious code into web pages, which can be executed in the context of the victim's browser session. This means that an attacker can steal sensitive data, such as login credentials or personal information, or perform unauthorized actions on behalf of the victim, such as modifying or deleting data. In this specific case, the vulnerability allows for a trivial account takeover attack. An attacker can exploit the vulnerability to inject code into the victim's browser session, allowing the attacker to take over the victim's account without their knowledge or consent. This can lead to unauthorized access to sensitive information and data, as well as the ability to perform actions on behalf of the victim. Furthermore, the fact that the vulnerability bypasses the Content Security Policy (CSP) makes it more dangerous, as CSP is an important security mechanism used to prevent cross-site scripting attacks. By bypassing CSP, attackers can circumvent the security measures put in place by the web application and execute their malicious code. This issue has been patched in versions 22.05.13, 21.11.9, and 6.4.27. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Threat Intelligence Overview

EPSS Score
0.4%
Top 68% exploitable
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.4%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

30
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +30
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Affected Products (CPE)NVD

cpe:2.3:a:collabora:online:*:*:*:*:*:*:*:*
cpe:2.3:a:collabora:online:*:*:*:*:*:*:*:*
cpe:2.3:a:collabora:online:*:*:*:*:*:*:*:*

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