CVE-2019-19521

Name: CVE-2019-19521
Creator: NVD / NIST
Published: 2019-12-05T00:15:11.4+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 2.74%

Last modified Jun 17, 2026

CVE-2019-19521 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. libc in OpenBSD 6.6 allows authentication bypass via the -schallenge username, as demonstrated by smtpd, ldapd, or radiusd. This is related to gen/auth_subr.c and gen/authenticate.c in libc (and login/login.c and xenocara/app/xenodm/greeter/verify.c).. EPSS estimates a 2.74% chance of exploitation in the next 30 days.

Description

libc in OpenBSD 6.6 allows authentication bypass via the -schallenge username, as demonstrated by smtpd, ldapd, or radiusd. This is related to gen/auth_subr.c and gen/authenticate.c in libc (and login/login.c and xenocara/app/xenodm/greeter/verify.c).

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

2.74%

84.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-287

Affected Software

Vendor	Product	Versions
Openbsd	Openbsd	6.6

References

http://packetstormsecurity.com/files/155572/Qualys-Security-Advisory-OpenBSD-Authentication-Bypass-Privilege-Escalation.htmlThird Party Advisory
http://seclists.org/fulldisclosure/2019/Dec/14Third Party Advisory
http://www.openwall.com/lists/oss-security/2019/12/04/5Exploit, Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2019/12/04/6Mailing List
https://seclists.org/bugtraq/2019/Dec/8Exploit, Mailing List, Third Party Advisory
https://www.openbsd.org/errata66.htmlVendor Advisory
https://www.openwall.com/lists/oss-security/2019/12/04/5Exploit, Mailing List, Third Party Advisory
http://packetstormsecurity.com/files/155572/Qualys-Security-Advisory-OpenBSD-Authentication-Bypass-Privilege-Escalation.htmlThird Party Advisory
http://seclists.org/fulldisclosure/2019/Dec/14Third Party Advisory
http://www.openwall.com/lists/oss-security/2019/12/04/5Exploit, Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2019/12/04/6Mailing List
https://seclists.org/bugtraq/2019/Dec/8Exploit, Mailing List, Third Party Advisory
https://www.openbsd.org/errata66.htmlVendor Advisory
https://www.openwall.com/lists/oss-security/2019/12/04/5Exploit, Mailing List, Third Party Advisory

Timeline

Published: Dec 5, 2019
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2019-19521?

How severe is CVE-2019-19521?

CVE-2019-19521 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 2.74% probability of exploitation in the next 30 days.

How do I fix CVE-2019-19521?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2019-19521?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST