Denial of Service Vulnerability in Web Interface of F-Secure Internet Gatekeeper

published 2021-09-28 5y ago modified 2026-06-17 4mo ago also EUVD-2021-20284

cvss: 5.4; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.6%; EPSS 0.6% chance of exploitation in 30 days, percentile 49%
public exploits: 0; none known

A denial-of-service (DoS) vulnerability was discovered in the web user interface of F-Secure Internet Gatekeeper. The vulnerability occurs because of an attacker can trigger assertion via malformed HTTP packet to web interface. An unauthenticated attacker could exploit this vulnerability by sending a large username parameter. A successful exploitation could lead to a denial-of-service of the product.

Is CVE-2021-33600 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Exploit prediction

0.61% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
NVD	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	2.0	5.0	AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected products

F-Secure F-Secure Internet Gatekeeper

Classification

Weakness

CWE-617 Reachable Assertion

References

f-secure.com /en/business/programs/vulnerability-reward-program/hall-of-fame
vendor-advisory
f-secure.com /en/business/support-and-downloads/security-advisories/cve-2021-33600
vendor-advisory

Sources

CVE List CVE-2021-33600
NVD CVE-2021-33600

Fencer Intel 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.