{"cve":"CVE-2013-4206","nvd":{"published":"2013-08-19T23:55:08.723","modified":"2026-06-16T23:56:48.847","status":"Modified","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.","cvss_v4":null,"cvss_v3":null,"cwes":["CWE-119"],"references":["http://lists.opensuse.org/opensuse-updates/2013-08/msg00035.html","http://secunia.com/advisories/54379","http://secunia.com/advisories/54533","http://svn.tartarus.org/sgt/putty/sshbn.c?sortby=date&r1=9977&r2=9976&pathrev=9977","http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-modmul.html"],"products":["putty:putty","simon_tatham:putty"],"source":"nvd","synced_at":"2026-10-19T20:29:16.037019470+00:00"},"epss":{"cve":"CVE-2013-4206","score":0.02475,"percentile":0.84545,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}