CVE-2017-20205

Oct. 15, 2025, 2:15 a.m.

9.2
Critical

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.

Product(s) Impacted

Vendor Product Versions
Valve
  • Source Sdk
  • *

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-121
Stack-based Buffer Overflow
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

*CPE(s)

Affected systems and software identified for this CVE.

Type Vendor Product Version Update Edition Language Software Edition Target Software Target Hardware Other Information
a valve source_sdk / / / / / / / /

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

Tags

CWE-121
disclosure@vulncheck.com
2025-10-15
CVE-2017-20205

CVSS Score

9.2 / 10

CVSS Data - 4.0

  • Attack Vector: NETWORK
  • Attack Complexity: LOW
  • Attack Requirements: PRESENT
  • Privileges Required: NONE
  • User Interaction: NONE
  • Scope:
  • Confidentiality Impact: HIGH
  • Integrity Impact: HIGH
  • Availability Impact: HIGH
  • Exploit Maturity: NOT_DEFINED

    • 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

    View Vector String

Timeline

Published: Oct. 15, 2025, 2:15 a.m.
Last Modified: Oct. 15, 2025, 2:15 a.m.

Status : Received

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

disclosure@vulncheck.com

*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.