CVE WatchJul 14, 2026

CVE-2026-29008

U-Boot through 2026.04-rc3 contains an integer underflow vulnerability in the tcp_rx_state_machine() function (net/tcp.c) that allows a netw

CVSS

7.5

High

EPSS

0.4%

p36

KEV

—

Exploit Today

0-100

Published: Jul 8, 2026 · Last modified: Jul 14, 2026 · CWE-191

EPSS · 30d

0.4%EPSS · 30 days0.4%

2026-07-092026-07-18

Technical description

U-Boot through 2026.04-rc3 contains an integer underflow vulnerability in the tcp_rx_state_machine() function (net/tcp.c) that allows a network-adjacent attacker to crash the bootloader by sending a malformed TCP SYN+ACK packet with a manipulated data offset field causing payload_len to become negative. When the TCP_SYN_SENT handler calls tcp_rx_user_data() without invoking tcp_seg_in_wnd() validation, the negative payload_len is implicitly converted to a large unsigned integer (e.g., 0xFFFFFFD8) and passed to memcpy() in store_block(), causing an immediate crash that prevents device boot and may enable memory corruption when CONFIG_LMB is disabled.

Official references

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