countly-server: Unauthenticated Denial of Service (DoS) via Unhandled Stream Exception

published 2026-10-16 23 d ago modified 2026-10-16 23 d ago also EUVD-2026-102916

cvss: 7.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 45%
public exploits: 0; none known

countly-server is the server-side part of Countly, a product analytics solution. Prior to 24.05.50 and 25.03.44, star-rating/images/ and dashboards/images/screenshots/ are among public image and screenshot routes using the local fs storage backend that call getStream and pipe filesystem streams to HTTP responses without an error listener. An unauthenticated request containing a URL-encoded dot can make createReadStream open a directory, emit an asynchronous EISDIR error, and terminate the Node.js process as an unhandled exception, allowing repeated requests to keep the analytics API unavailable. The affected routes also include /appimages/*, /memberimages/*, and */screenshots/*. This issue is fixed in versions 24.05.50 and 25.03.44.

Patch / fix

fixed in 1 links 4

count countly_server 24.05.50, 25.03.44

CISA SSVC

Exploitation: Proof of concept is public
Automatable: yes
Technical impact: partial
Assessed: 23 d ago (2026-10-16)

Exploit prediction

0.54% chance of exploitation in the next 30 days, higher than 45% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/Countly/countly-server/security/advisories/GHSA-86cv-qwp9-jwp3 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

Countly countly-server

Classification

Weakness

CWE-248 Uncaught Exception

References

Sources

CVE List CVE-2026-42270
NVD CVE-2026-42270

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary