CVE-2013-4206
CWE-119Published: August 19, 2013· Updated: Jun 16, 2026
Official Description
Heap-based buffer underflow in the modmul function in sshbn.c in PuTTY before 0.63 allows remote SSH servers to cause a denial of service (crash) and possibly trigger memory corruption or code execution via a crafted DSA signature, which is not properly handled when performing certain bit-shifting operations during modular multiplication.
Technical Analysis
CVE-2013-4206 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
From a weakness classification perspective (CWE-119): Buffer overflow vulnerabilities can lead to arbitrary code execution or denial of service by corrupting adjacent memory.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
Official Patches & Advisories
All References (14)
Quick Facts
Related CVEs (CWE-119)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2013-4206 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts