What is CVE-2026-44977?

CVE-2026-44977 is a critical-severity vulnerability in Countly Countly-Server, classified under Cross-site Scripting. CVSS score: 9.0/10. Published 2026-10-16.

How severe is CVE-2026-44977?

Critical severity. CVSS v3 base score is 9.0 out of 10.

XSS in Countly Countly-Server

CVE-2026-44977

countly-server is the server-side part of Countly, a product analytics solution. Prior to 24.05.50 and 25.03.44, plugins/star-rating/api/api.js allows a non-global application administrator to use uploadFeedbackFile to store attacker-controlled active content while trusting the supplied MIME type. plugins/star-rating/frontend/app.js publicly serves the stored content from feedback/preview/ with the attacker-influenced Content-Type, so a global administrator who opens the preview executes the payload in the Countly origin and exposes authenticated session capabilities, including auth_token and csrf_token values. This issue is fixed in versions 24.05.50 and 25.03.44.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2026-10-16 · last modified 2026-10-16.

CVSS v3 metric

CVSS v3 base score 9.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Countly Countly-Server — versions < 24.05.50, >= 25.03, < 25.03.44

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

Frequently asked questions

What is CVE-2026-44977?: CVE-2026-44977 is a critical-severity vulnerability in Countly Countly-Server, classified under Cross-site Scripting. CVSS score: 9.0/10. Published 2026-10-16.
How severe is CVE-2026-44977?: Critical severity. CVSS v3 base score is 9.0 out of 10.