Vulnerability · Published Oct 16, 2026 · Assigned by GitHub_M

CVE-2026-44977countly-server: Stored XSS in feedback upload enables app-admin to compromise global admin session context

Critical 9.0

In plain English

A critical-severity cross-site scripting in countly-server from Countly. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 38% of all known vulnerabilities).

Severity (CVSS 3.1)9.0Critical

Exploit odds (30 days)0.4%top 61.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
Countly	countly-server	< 24.05.50>= 25.03, < 25.03.44

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

References

https://github.com/Countly/countly-server/security/advisories/GHSA-jqp4-p86c-phxc x_refsource_CONFIRM
https://github.com/Countly/countly-server/commit/ae899f37bc6d70c1b44859756ce80a204ae72631 x_refsource_MISC
https://github.com/Countly/countly-server/commit/fcb16c808c0fdb6dc99fe9c66de7fc560b3a9c41 x_refsource_MISC
https://github.com/Countly/countly-server/releases/tag/24.05.50 x_refsource_MISC
https://github.com/Countly/countly-server/releases/tag/25.03.44 x_refsource_MISC