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PatchSiren cyber security CVE debrief

CVE-2016-2233 Hexchat Project CVE debrief

CVE-2016-2233 is a stack-based buffer overflow in HexChat 2.10.2’s inbound_cap_ls function while handling CAP LS messages. A remote IRC server can trigger a crash by sending a CAP LS message with a large number of options. The NVD records the issue as CVSS 3.0 7.5 (High) with CWE-119, and the impact is denial of service rather than confidentiality or integrity loss.

Vendor
Hexchat Project
Product
Hexchat
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2017-01-18
Original CVE updated
2026-05-13
Advisory published
2017-01-18
Advisory updated
2026-05-13

Who should care

Anyone running HexChat 2.10.2, especially users or administrators who connect to untrusted IRC servers or rely on HexChat in environments where a client crash would be disruptive.

Technical summary

The vulnerable code path is in common/inbound.c, function inbound_cap_ls, where parsing of CAP LS options can overflow a stack buffer. The attack is network-reachable over IRC, requires no privileges, and no user interaction is listed in the CVSS vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). The vulnerability is categorized as CWE-119 and the reported effect is client crash/denial of service.

Defensive priority

High. This is a network-reachable memory-safety flaw in a client-facing parser that processes untrusted server input. Prioritize remediation anywhere HexChat 2.10.2 is still in use.

Recommended defensive actions

  • Identify systems and user endpoints running HexChat 2.10.2.
  • Upgrade to a vendor-fixed HexChat release as soon as one is available in your environment.
  • If immediate upgrading is not possible, reduce exposure by limiting connections to trusted IRC servers only.
  • Monitor for unexpected HexChat crashes or repeated restarts that may indicate triggering traffic.
  • Remove or replace unsupported deployments that cannot be patched promptly.

Evidence notes

Source corpus evidence ties the issue to HexChat 2.10.2 via the NVD CPE entry and describes a stack-based buffer overflow in inbound_cap_ls in common/inbound.c. NVD lists CVSS 3.0 vector CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H and CWE-119. The provided references include a Packet Storm advisory, SecurityFocus BID 95920, and Exploit-DB entry 39657; their presence confirms public third-party discussion, but this debrief does not summarize exploit details.

Sources and references

Verified primary and authoritative sources

  • CVE-2016-2233 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2016-2233

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2016-2233 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2016-2233

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.