CVE-2026-23623VulnerabilityPublished 5 Feb 2026

CVE-2026-23623: CollaboraOnline online · Improper Authorization

Affects CollaboraOnline onlineSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium : upgrade to 23.05.20.1 when convenient.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 23.05.20.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

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

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 5 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade collaboraonline/online to 23.05.20.1.

Affected software

Product	Affected	Fixed in
CollaboraOnlineonline	Affected =Collabora Online < 25.04.7.5 =Collabora Online < 24.04.17.3 =Collabora Online < 23.05.20.1 =Collabora Online Development Edition < 25.04.08.2	Fixed in–
GitHubcollaboraonline/online`pkg:github/collaboraonline/online`Other threats	Affected <23.05.20.1	Fixed in 23.05.20.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

European organizations should immediately upgrade Collabora Online installations to the patched versions: 23.05.20.1, 24.04.17.3, 25.04.7.5, or Development Edition 25.04.08.2. Until patching is complete, administrators should review and tighten user permission settings, minimizing the number of users with view-only access to sensitive documents. Implement monitoring and alerting for unusual file download activities, especially keyboard shortcut usage or unexpected file access patterns. Consider disabling or remapping the Ctrl+Shift+S shortcut at the application or system level as a temporary workaround. Conduct user training to raise awareness about the vulnerability and encourage reporting of suspicious behavior. Regularly audit document sharing policies and access logs to detect unauthorized data retrieval attempts. Collaborate with IT and security teams to integrate vulnerability management processes ensuring timely updates of collaboration platforms. Finally, evaluate alternative secure collaboration tools if patching is delayed or not feasible.

Description

CVE-2026-23623 is a medium severity vulnerability in Collabora Online that allows users with view-only permissions and no download rights to bypass access controls and download shared files by pressing Ctrl+Shift+S, despite the interface lacking download buttons. This improper authorization issue affects multiple versions prior to patched releases in 2026. The vulnerability impacts confidentiality by enabling unauthorized data retrieval without requiring authentication or user interaction beyond the keypress. It has a CVSS score of 5.3 and has not been observed exploited in the wild. European organizations using vulnerable versions of Collabora Online for document collaboration risk unauthorized data exposure. Mitigation requires updating to fixed versions 23.05.20.1, 24.

Impact

For European organizations, this vulnerability poses a risk of unauthorized data disclosure from collaborative document environments. Organizations using Collabora Online for internal or external document sharing may inadvertently expose sensitive or confidential information to users who should only have view-only access without download capabilities. This can lead to data leakage incidents, regulatory non-compliance (e.g., GDPR violations), and reputational damage. The impact is particularly relevant for sectors handling sensitive data such as government, finance, healthcare, and legal services. Since the exploit requires no authentication or complex steps beyond a keyboard shortcut, insider threats or compromised accounts with limited permissions can easily abuse this flaw. The vulnerability does not affect data integrity or availability but undermines trust in access control mechanisms. The lack of known exploits in the wild reduces immediate risk but does not eliminate the potential for targeted attacks or opportunistic abuse.

CWE-285Improper Authorization (opens in a new tab)
Class weaknessLikelihood of exploit: HighOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design
Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) to enforce the roles at the appropriate boundaries.
Architecture and Design
Ensure that you perform access control checks related to your business logic. These checks may be different than the access control checks that you apply to more generic resources such as files, connections, processes, memory, and database records.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.8 (opens in a new tab)
V13.4.2 (opens in a new tab)
V7.2.2 (opens in a new tab)
Attack patterns
Accessing Functionality Not Properly Constrained by ACLs (opens in a new tab)
Cross Zone Scripting (opens in a new tab)
Directory Indexing (opens in a new tab)
Subverting Environment Variable Values (opens in a new tab)
Using Malicious Files (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/CollaboraOnline/online/security/advisories/GHSA-68v6-r6qq-mmq2 (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 13 Feb 2026, 07:23 UTC

WeaknessesCWE-285

Technical details

References

Community reviews

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