Is CVE-2017-15721 in the CISA KEV catalog?

No. CVE-2017-15721 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2017-15721?

CVE-2017-15721 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2017-15721?

CVE-2017-15721 has an EPSS score of 2.37% (82th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2017-15721?

Upgrade irssi on debian 11 to 1.0.5-1 or later. Fixes are available for 2 affected products.

CVE & CISA-KEV Catalog

CVE-2017-15721

HIGHEPSS 82th pctl

7.5

CVSS v3

NVD

Description

In Irssi before 1.0.5, certain incorrectly formatted DCC CTCP messages could cause a NULL pointer dereference. This is a separate, but similar, issue relative to CVE-2017-9468.

CWE-476NULL Pointer Dereference

How to fix

Remediation Available

irssiDebian

Fixed in:1.0.5-1CVE-2017-15721

irssiUbuntu

Fixed in:0.8.15-5ubuntu3.3USN-3465-1

Fixed in:0.8.19-1ubuntu1.5USN-3465-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploit Intelligence

2.37%probability of exploitation in 30 days

82ndpercentile

Elevated risk: more likely to be exploited than 82% of all known CVEs.

References

Patch2

Third-Party Advisory2

Related Vulnerabilities

Other CWE-476 (NULL Pointer Dereference) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-21758	High	7.5	92%	-	Fix
CVE-2023-21547	High	7.5	88%	-	Fix
CVE-2014-3470	Medium	4.3	86%	-	Fix
CVE-2021-44224	High	8.2	82%	-	Fix
CVE-2016-0742	High	7.5	82%	-	Fix
CVE-2009-1386	Medium	5.0	80%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-13.