Cisco Umbrella Carriage Return Line Feed Injection Vulnerability

published 2020-05-06 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-24517

cvss: 4.7; version 3.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.9%; EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits: 0; none known

A vulnerability in the web server of Cisco Umbrella could allow an unauthenticated, remote attacker to perform a carriage return line feed (CRLF) injection attack against a user of an affected service. The vulnerability is due to insufficient validation of user input. An attacker could exploit this vulnerability by persuading a user to access a crafted URL. A successful exploit could allow the attacker to inject arbitrary HTTP headers into valid HTTP responses sent to the browser of the user.

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 23 mo ago (2024-11-15)

Exploit prediction

0.90% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.0	4.7	CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
NVD	3.1	4.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
NVD	2.0	4.3	AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

Cisco Cisco Umbrella

Classification

Weakness

CWE-93 Improper Neutralization of CRLF Sequences
CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

References

tools.cisco.com /security/center/content/CiscoSecurityAdvisory/cisco-sa-umbrella-head-inject-n4QArJH
vendor-advisory

Sources

CVE List CVE-2020-3246
NVD CVE-2020-3246

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Summary