What’s Vulnerable › Vulnerabilities
CVE-2017-20205: Valve Source SDK Stack-Based Buffer Overflow RCE
- Severity: critical (CVSS 9.2 v4.0)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.7% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2025-10-15 · updated 2026-06-17
- Weakness: CWE-121
Description
Valve's Source SDK (source-sdk-2013)'s ragdoll model parsing logic contains a stack-based buffer overflow vulnerability.The tokenizer function `nexttoken` copies characters from an input string into a fixed-size stack buffer without performing bounds checks. When `ParseKeyValue` processes a collisionpair rule longer than the destination buffer (256 bytes), an overflow of the stack buffer `szToken` can occur and overwrite the function return address. A remote attacker can trigger the vulnerable code by supplying a specially crafted ragdoll model which causes the oversized collisionpair rule to be parsed, resulting in remote code execution on affected clients or servers. Valve has addressed this issue in many of their Source games, but independently-developed games must manually apply patch.
Affected products
- Valve Software Source SDK (source-sdk-2013): source-sdk-2013
References
- https://github.com/ValveSoftware/source-sdk-2013
- https://www.oneupsecurity.com/research/remote-code-execution-in-source-games/
- https://www.vulncheck.com/advisories/valve-source-sdk-stack-based-buffer-overflow-rce
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