Integer Underflow Affecting u-boot package, versions *


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.71% (51st percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-UBOOT-17971798
  • published14 Jul 2026
  • disclosed8 Jul 2026

Introduced: 8 Jul 2026

CVE-2026-29008  (opens in a new tab)
CWE-191  (opens in a new tab)

How to fix?

There is no fixed version for Debian:unstable u-boot.

NVD Description

Note: Versions mentioned in the description apply only to the upstream u-boot package and not the u-boot package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1