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Irssi CVE-2018-5206

CRITICAL
NULL Pointer Dereference (CWE-476)
2018-01-06 cve@mitre.org
Denial Of Service Null Pointer Dereference Debian Debian Linux Irssi
9.8
CVSS 3.0 · NVD
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Vulnerability Assessment

Weakness
CWE
CWE-476
OWASP Top 10:2025
A10:2025 - Mishandling of Exceptional Conditions
ASVS 5.0
V16 - Security Logging and Error Handling Null pointer safety, defensive checks
MITRE ATT&CK

1 technique across 1 tactic: Impact

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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Impact

CVSS score of 9.8 (CRITICAL). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required.
Exploit ScenarioDerived

A remote attacker could crash the application by dereferencing a null pointer by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.
Act Now Prioritize within 24-48h. Why: CRITICAL severity.
Patch available 2.2% exploitation probability (EPSS)

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AnalysisAI

When the channel topic is set without specifying a sender, Irssi before 1.0.6 may dereference a NULL pointer. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This NULL Pointer Dereference vulnerability could allow attackers to crash the application by dereferencing a null pointer.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Check pointers before dereferencing. Use static analysis tools to detect null pointer paths.

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Technical ContextAI · show details

This vulnerability is classified as NULL Pointer Dereference (CWE-476), which allows attackers to crash the application by dereferencing a null pointer. When the channel topic is set without specifying a sender, Irssi before 1.0.6 may dereference a NULL pointer. Affected products include: Irssi, Debian Debian Linux. Version information: before 1.0.6.

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

NVD PRIMARY 9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionNVD

When the channel topic is set without specifying a sender, Irssi before 1.0.6 may dereference a NULL pointer.

Threat Intelligence Overview

EPSS Score
2.2%
Top 20% exploitable
Data Quality
2 sources
Confidence: Low
NVD CVE.org EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 2.2%
Patch available Yes
Active threat No
Deciding rule
CRITICAL severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact· derived
Medium

Priority Score

51
Low Medium High Critical
KEV: 0
EPSS: +2
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Null Pointer Dereference MEDIUM

A null pointer dereference occurs when a program attempts to access memory through a pointer that has been set to NULL (address 0x0).

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Affected Products (CPE)NVD

cpe:2.3:a:irssi:irssi:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

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Same weakness CWE-476 – NULL Pointer Dereference

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CVE-2017-3169 CRITICAL POC
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CVE-2016-4957 HIGH
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CVE-2021-3449 MEDIUM
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CVE-2015-3194 HIGH
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Same technique Denial Of Service

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CVE-2011-0611 HIGH POC
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CVE-2012-1889 HIGH POC
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CVE-2012-0507 CRITICAL POC
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CVE-2014-1761 HIGH POC
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CVE-2015-5122 CRITICAL POC
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CVE-2011-0609 HIGH POC
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References

Advisories & patches
PATCH https://irssi.org/security/irssi_sa_2018_01.txt REF https://www.debian.org/security/2018/dsa-4162

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