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CRITICAL

Valve Source SDK Stack-Based Buffer Overflow RCE

Published Oct 15, 2025

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

Remediation

No remediation recorded yet.

Metrics

Weaknesses (1)

References (3)

Change history (0)

No recorded changes yet.

Sources
CVE.org / MITRE
Status PUBLISHED
Assigner VulnCheck
Published Oct 15, 2025
Updated Nov 21, 2025
Reserved Oct 14, 2025
CISA Vulnrichment
Updated Oct 15, 2025
NVD
Status Deferred
Modified Jun 17, 2026
Red Hat
Severity n/a
Public date n/a