Heap-based buffer overflow in WeeChat - #VU164401
Published: November 10, 2026
Vulnerability identifier: #VU164401
CSH Severity: High
CVSS v4: 9.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-122
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service and potentially execute arbitrary code through heap corruption.
The vulnerability exists due to a heap-based buffer overflow caused by undersized allocation and unchecked replacement-byte writes in WeeChat's string_iconv function when decoding inbound IRC messages using TSCII. A remote attacker can send crafted messages, such as bytes([0x88]) * 2000 + bytes([0xA0]) * 1000, through a controlled IRC server or channel text relayed by an honest server to overflow the heap buffer and potentially hijack control flow.
Affected software
WeeChat
Remediation
Install security update from vendor's website.
WeeChat - update to 4.10.2