CVE-2026-43887
CVE-2026-43887 is a high-severity vulnerability with a CVSS 3.x base score of 7.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.
Key facts
- Severity: High (CVSS 3.x base score 7.3)
- EPSS exploit prediction: 0% (16th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-29331
- Weakness: CWE-79
- Published:
- Last modified:
Description
Outline is a service that allows for collaborative documentation. From 0.84.0 to 1.6.1, the Outline comment section permits users to mention other users; however, the backend does not validate or sanitize the href attribute associated with these mentions. As a result, potentially dangerous protocols (e.g., javascript:) are not filtered, introducing a risk of client-side code execution. This vulnerability is fixed in 1.7.0.
Frequently asked questions
- What is CVE-2026-43887?
- Outline is a service that allows for collaborative documentation. From 0.84.0 to 1.6.1, the Outline comment section permits users to mention other users; however, the backend does not validate or sanitize the href attribute associated with these mentions. As a result, potentially dangerous protocols (e.g., javascript:) are not filtered, introducing a risk of client-side code execution. This vulnerability is fixed in 1.7.0.
- How severe is CVE-2026-43887?
- CVE-2026-43887 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.
- Is CVE-2026-43887 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-43887?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-43887 have an EU (EUVD) identifier?
- Yes. CVE-2026-43887 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29331.
- When was CVE-2026-43887 published?
- CVE-2026-43887 was published on 2026-05-11 and last updated on 2026-06-17.
References
Other CWE-79 (Cross-site Scripting (XSS)) vulnerabilities
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