CVE-2009-1959

CVE-2009-1959 is a medium-severity vulnerability in Irssi with a CVSS 2.0 base score of 5.0. 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-189.

Key facts

• Severity: Medium (CVSS 2.0 base score 5.0)
• EPSS exploit prediction: 8% (94th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-189
• Affected product: Irssi
• Published: 2009-06-08
• Last modified: 2026-06-16

Description

Off-by-one error in the event_wallops function in fe-common/irc/fe-events.c in irssi 0.8.13 allows remote IRC servers to cause a denial of service (crash) via an empty command, which triggers a one-byte buffer under-read and a one-byte buffer underflow.

Frequently asked questions

What is CVE-2009-1959?

Off-by-one error in the event_wallops function in fe-common/irc/fe-events.c in irssi 0.8.13 allows remote IRC servers to cause a denial of service (crash) via an empty command, which triggers a one-byte buffer under-read and a one-byte buffer underflow.

How severe is CVE-2009-1959?

CVE-2009-1959 has a CVSS 2.0 base score of 5.0, rated medium severity.

Is CVE-2009-1959 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 8% (94th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-1959?

CVE-2009-1959 affects Irssi. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2009-1959?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2009-1959 published?

CVE-2009-1959 was published on 2009-06-08 and last updated on 2026-06-16.

References

• http://bugs.irssi.org/index.php?do=details&task_id=662
• http://lists.opensuse.org/opensuse-security-announce/2009-07/msg00002.html
• http://secunia.com/advisories/35685
• http://secunia.com/advisories/35812
• http://secunia.com/advisories/36152
• http://www.irssi.org/ChangeLog
• http://www.mandriva.com/security/advisories?name=MDVSA-2009:133
• http://www.openwall.com/lists/oss-security/2009/05/29/3
• http://www.securityfocus.com/bid/35399
• http://www.securitytracker.com/id?1022410
• http://www.ubuntu.com/usn/usn-800-1
• http://www.vupen.com/english/advisories/2009/1596
• http://xorl.wordpress.com/2009/05/28/irssi-event_wallops-off-by-one-readwrite/
• https://exchange.xforce.ibmcloud.com/vulnerabilities/51184
• https://www.redhat.com/archives/fedora-package-announce/2009-August/msg00146.html

Affected products (1)

• cpe:2.3:a:irssi:irssi:0.8.13:*:*:*:*:*:*:*

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