Description (CNA)
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.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| u-boot / u-boot | affected 0 through 2026.04-rc3 |
CWE
CWE-191
References
- https://y637f9qq2x.com/posts/u-boot-tcp-nfs-vulns/
- https://lists.denx.de/pipermail/u-boot/2026-May/617853.html
- https://u-boot.org/
- https://www.vulncheck.com/advisories/u-boot-rc3-integer-underflow-dos-via-tcp-rx-state-machine
ADP enrichment
No English description supplied.
No references supplied.