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CVE-2026-29008

HIGH
7.5
CVSS 3.1
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.

Metadata

CVE ID
CVE-2026-29008
State
PUBLISHED
Assigner
VulnCheck
Reserved
2026-03-03 16:42 UTC
Published
2026-07-08 16:14 UTC
Last updated
2026-07-09 13:56 UTC
Primary CWE
CWE-191
Integer Underflow (Wrap or Wraparound)
Vendor / Product
u-boot / u-boot
Sources
cve.org  ·  NVD

Severity & Metrics

7.5 HIGH CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC — CISA Coordinator
Exploitation
none
Automatable
yes
Tech. Impact
partial
Affected products (1)
VendorProductPlatformVersions
u-boot u-boot — 0 ≤ 2026.04-rc3
Weakness (CWE)
CWESourceDescription
CWE-191 cna Integer Underflow (Wrap or Wraparound)
CVSS scores (2)
ScoreSeverityVersionSourceVector
8.7 HIGH 4.0 cna CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5 HIGH 3.1 cna CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References (3)
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