Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.40% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2023
CVE-2023-31145High confidence
Reflected XSS vulnerability in CollaboraOnline
CollaboraOnline · online
Official source article: GitHub GHSA-RQJ2-2C2X-GJMM ↗. Check the applicable product and release in the original source.
4.3MediumCVSS 3.1
Scheduled
Fix not verifiedMedium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityMedium→Operational priority:Medium, unchanged from published severity.unchanged
Compensating controls
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs CollaboraOnline online and falls inside the recorded affected range.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.
Fix not verified01
What, why and how
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.
What
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.
Why
Attacker-controlled content can reach a browser as executable script without sufficient output encoding or sanitisation.
How
An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may bypass an access boundary or take over an account.
What
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.
Why
Attacker-controlled content can reach a browser as executable script without sufficient output encoding or sanitisation.
How
An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may bypass an access boundary or take over an account.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') → bypass an access boundary or take over an account
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- Required interaction required
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-79 ↗
CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'). The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:NCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.ILowIntegrity impact: A successful attack can cause a limited loss.ANoneAvailability impact: No direct loss is represented by this metric.- Post-exploitation / living off the land
- Stolen credentials, tokens and legitimate administration functions may provide continued access without deploying a large custom toolset.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Fix not verified
- Affected
- online: < 6.4.27, >= 21.0.0, < 21.11.9, >= 22.0.0, < 22.05.13
- Fixed
- No fixed version is explicitly recorded in the structured CVE data.
- Action
- No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 15 May 2023 · Last source change 22 Jan 2025, 21:18 UTC · CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2023-35462
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD modified after enrichment
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.