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Description

U-Boot through 2026.04-rc3 contains an out-of-bounds read vulnerability in tcp_rx_state_machine() (net/tcp.c) when CONFIG_PROT_TCP is enabled, allowing remote attackers to read beyond TCP segment boundaries by crafting a malicious packet with a mismatched IP total length and TCP data offset field. Attackers can send a packet with an IP total length of 40 bytes and a TCP data offset claiming 60 bytes of header to cause tcp_parse_options() to read 40 bytes past the end of the TCP segment, potentially corrupting connection state variables such as rmt_win_scale and rmt_timestamp to disrupt TCP window calculations.

PUBLISHED Reserved 2026-03-03 | Published 2026-07-08 | Updated 2026-07-14 | Assigner VulnCheck




MEDIUM: 6.9CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

MEDIUM: 5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Problem types

Out-of-bounds Read

Product status

Default status
affected

Any version
affected

Credits

Kazuma Matsumoto, a security researcher at GMO Cybersecurity by IERAE, Inc. finder

VulnCheck coordinator

References

y637f9qq2x.com/posts/u-boot-tcp-nfs-vulns/ technical-description exploit

lists.denx.de/pipermail/u-boot/2026-May/617853.html (Mailing List Outreach) issue-tracking

u-boot.org/ (Project Webpage) product

www.vulncheck.com/...-read-in-tcp-rx-state-machine-via-tcp-c third-party-advisory

cve.org (CVE-2026-29007)

nvd.nist.gov (CVE-2026-29007)

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