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CVE-2026-29008— U-Boot 2026.04-rc3 Integer Underflow DoS via tcp_rx_state_machine()

Quick assessment

Affected
u-boot u-boot
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

U-Boot U-Boot是U-Boot社区开源的一个免费、开源且可扩展的引导加载程序，适用于多种架构（ARM、MIPS、PowerPC、RISC-V、x86、x86_64），其目的是执行各种硬件初始化任务并启动设备的操作系统内核。 U-Boot 2026.04-rc3及之前版本存在数字错误漏洞，该漏洞源于tcp_rx_state_machine()函数中存在整数下溢，网络邻近攻击者通过发送数据偏移字段被操纵的畸形TCP SYN+ACK数据包导致payload_len变为负数，从而引发引导加载程序崩溃并可

CVSS 7.5 · High EPSS 0.71% · P52

Affected Version Matrix 1

VendorProduct Version RangeStatus
u-boot u-boot ≤ 2026.04-rc3 affected
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I. Basic Information for CVE-2026-29008

Vulnerability Information
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Vulnerability Title
U-Boot 2026.04-rc3 Integer Underflow DoS via tcp_rx_state_machine()
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
整数下溢(超界折返)
Source: CVE Program / CVE List V5
Vulnerability Title
U-Boot 数字错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
U-Boot U-Boot是U-Boot社区开源的一个免费、开源且可扩展的引导加载程序，适用于多种架构（ARM、MIPS、PowerPC、RISC-V、x86、x86_64），其目的是执行各种硬件初始化任务并启动设备的操作系统内核。 U-Boot 2026.04-rc3及之前版本存在数字错误漏洞，该漏洞源于tcp_rx_state_machine()函数中存在整数下溢，网络邻近攻击者通过发送数据偏移字段被操纵的畸形TCP SYN+ACK数据包导致payload_len变为负数，从而引发引导加载程序崩溃并可
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
u-boot u-boot 0 ~ 2026.04-rc3 -

II. Public POCs for CVE-2026-29008

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III. Intelligence Information for CVE-2026-29008

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Vendor Advisories for CVE-2026-29008 (1)

Mailing List Discussions for CVE-2026-29008 (1)

Security Blog Posts for CVE-2026-29008 (1)

Vendor Pages for CVE-2026-29008 (1)

Same Patch Batch · u-boot · 2026-07-08 · 3 CVEs total

CVE-2026-29009 8.2 HIGH U-Boot < 2026.07-rc2 Buffer Overflow in nfs_readlink_reply() via NFS READLINK
CVE-2026-29007 5.3 MEDIUM U-Boot 2026.04-rc3 Out-of-Bounds Read in tcp_rx_state_machine via tcp.c

IV. Related Vulnerabilities

Same product: u-boot
Same vendor: u-boot
Same weakness: CWE-191

V. Comments for CVE-2026-29008

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