What is CVE-2026-43887?

CVE-2026-43887 is a high-severity vulnerability in Outline, classified under Cross-site Scripting. CVSS score: 7.3/10. Published 2026-05-11.

How severe is CVE-2026-43887?

High severity. CVSS v3 base score is 7.3 out of 10.

XSS in Outline

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…

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.000 (11.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.3 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N.

Affected products

Outline — versions >= 0.84.0, < 1.7.0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

security-advisories@github.com (x_refsource_CONFIRM)

Frequently asked questions

What is CVE-2026-43887?: CVE-2026-43887 is a high-severity vulnerability in Outline, classified under Cross-site Scripting. CVSS score: 7.3/10. Published 2026-05-11.
How severe is CVE-2026-43887?: High severity. CVSS v3 base score is 7.3 out of 10.