CVE-2017-20205Valve Source SDK Stack-Based Buffer Overflow RCE
Updated under an hour ago ()
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It affects Valve Software Source SDK (source-sdk-2013). Add what you run to find out whether that includes you.
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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.
- CVSS
- 9.2 CRITICAL (v4.0, CNA)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
- Weakness (CWE)
- CWE-121
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- VulnCheck
- NVD analysis
- Deferred
- Record last updated
- Nov 21, 2025
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Valve Software Source SDK (source-sdk-2013) valve_software:source_sdk_source_sdk_2013 (from the name) | source-sdk-2013 | CNA record |
References
- https://www.oneupsecurity.com/research/remote-code-execution-in-source-games/technical-description, patch
- https://github.com/ValveSoftware/source-sdk-2013product
- https://www.vulncheck.com/advisories/valve-source-sdk-stack-based-buffer-overflow-rcethird-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.