CVE-2026-4747
CVE-2026-4747: Stack Buffer Overflow in RPCSEC_GSS
Executive Summary
CVE-2026-4747 is a high severity vulnerability affecting software systems. It is classified as Stack-based Buffer Overflow. Ensure your systems and dependencies are patched immediately to mitigate exposure risks.
Precogs AI Insight
"Precogs AI detected this vulnerability pattern in Stack-based Buffer Overflow implementations. The pattern deviates from documented secure coding standards, suggesting a high likelihood of exploitation if unpatched."
Summary
A high-severity stack-based buffer overflow vulnerability (CVE-2026-4747) has been identified in the Linux kernel's RPCSEC_GSS signature validation routine. Malformed NFS/RPCSEC_GSS packets can overflow a stack buffer during signature verification (CWE-121).
Technical Details
The issue is classified under CWE-121 (Stack-based Buffer Overflow). The RPCSEC_GSS protocol provides security services for RPC-based protocols (primarily NFS). Each data packet includes a cryptographic signature that the kernel validates. The validation routine copies signature data into a fixed-size stack buffer using an operation that does not verify the input length.
When an attacker sends a packet with an oversized signature field, the copy operation writes beyond the buffer boundary, overwriting the stack frame.
Exploitation Context
- Vector: Remote / Network-based
- Authentication: Not required
- Complexity: Low
- Impact: High (Confidentiality, Integrity, and Availability)
NFS servers are widely deployed in enterprise environments. A kernel-level buffer overflow in the NFS authentication subsystem provides a direct path to full host compromise from the network.
Remediation
Linux administrators should immediately:
- Apply the latest kernel patch that adds proper bounds checking to the RPCSEC_GSS signature validation routine.
- Restrict NFS port access (typically 2049/tcp) to trusted client networks using firewall rules.
- Enable kernel stack protections (stack canaries, KASLR) to increase exploitation difficulty.
Precogs AI Integration
The Precogs AI Binary Security Platform identifies stack-based buffer overflow conditions in compiled kernel modules by analyzing signature verification routines for unsafe memory operations, detecting missing bounds checks before memcpy, strcpy, and similar functions.