CVE-2026-29009: U-Boot < 2026.07-rc2 Buffer Overflow in nfs_readlink_reply() via NFS READLINK

Vulnerability summary

CVE-2026-29009 is a critical (CVSS 9.8) Classic Buffer Overflow vulnerability in denx u-boot. EPSS estimates a 0.74% chance of exploitation in the next 30 days, higher than 54% of scored vulnerabilities. 2 public exploits are recorded.

Timeline

1. 08-07-2026
   PublishedVulnerability first disclosed.
2. 24-07-2026
   Last modifiedVulnerability information updated.

Description

U-Boot before 2026.07-rc2 contains a buffer overflow vulnerability in nfs_readlink_reply() (net/nfs-common.c) when CONFIG_CMD_NFS is enabled, allowing a malicious or compromised NFS server to overflow the 2048-byte nfs_path_buff buffer by returning multiple relative symlink targets that are appended without cumulative length validation. Attackers can send two or more READLINK responses containing relative symlink targets of approximately 1100 bytes each to corrupt adjacent BSS variables including nfs_server_ip, nfs_server_mount_port, nfs_server_port, nfs_our_port, nfs_state, and rpc_id, potentially achieving memory corruption and control over the NFS client state machine.

• CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.