How severe is CVE-2019-19521?

CVE-2019-19521 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2019-19521 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-19521?

CVE-2019-19521 affects Openbsd. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2019-19521?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2019-19521 published?

CVE-2019-19521 was published on 2019-12-05 and last updated on 2026-06-17.

CVE-2019-19521

CVE-2019-19521 is a critical-severity vulnerability in Openbsd with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-287.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 3% (84th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Openbsd
Published: 2019-12-05
Last modified: 2026-06-17

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).

Frequently asked questions

What is CVE-2019-19521?: 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).
How severe is CVE-2019-19521?: CVE-2019-19521 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2019-19521 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-19521?: CVE-2019-19521 affects Openbsd. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2019-19521?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2019-19521 published?: CVE-2019-19521 was published on 2019-12-05 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:openbsd:openbsd:6.6:*:*:*:*:*:*:*

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