CVE-2017-5193 Debian CVE debrief

Who should care

Anyone running Irssi before 0.8.21 should care, especially users who connect to untrusted or public IRC networks where malformed messages may be encountered. Package maintainers and security teams responsible for Linux distributions that ship Irssi should also verify they have the fixed release or backported patch.

Technical summary

NVD describes the flaw as a NULL pointer dereference in Irssi's nickcmp function, reachable when processing a message without a nick. The affected version range in the supplied corpus is Irssi before 0.8.21. The CVSS vector indicates network reachability, low attack complexity, no privileges, no user interaction, and a high availability impact.

Defensive priority

High for environments that still run affected Irssi clients, because the flaw is remotely triggerable and can crash the application. Priority is lower only if you have already confirmed Irssi 0.8.21 or later, or a vetted downstream backport, is deployed everywhere.

Recommended defensive actions

• Upgrade Irssi to version 0.8.21 or later, or install the vendor/distribution security fix referenced in the advisory corpus.
• Verify package versions across all systems that run Irssi and confirm no older build remains in use.
• If you rely on downstream packaging, check that the fix is present in your distro's security update stream before deferring remediation.
• Review crash logs or support tickets for unexpected Irssi exits that may align with NULL pointer dereference behavior in nickcmp.
• Track upstream and distribution advisories for any backported fix guidance relevant to your platform.

Evidence notes

The debrief is based on the supplied CVE description, which states that nickcmp in Irssi before 0.8.21 can be crashed by a message without a nick. NVD data in the corpus assigns CWE-476 and CVSS 3.0 vector AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, and the CPE criteria explicitly mark irssi versions ending before 0.8.21 as vulnerable. The vendor advisory and OSS-security reference are included as corroborating sources. No exploit code or reproduction steps are included.

Official resources