{"id":"CVE-2026-29008","aliases":["DEBIAN-CVE-2026-29008","EUVD-2026-42332","GHSA-3qwj-q697-4ppr","UBUNTU-CVE-2026-29008"],"status":"published","title":"U-Boot 2026.04-rc3 Integer Underflow DoS via tcp_rx_state_machine()","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.","severity":{"version":"4.0","score":8.7,"vector":"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","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00706,"percentile":0.53809,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-191"],"published":"2026-07-08T16:14:41Z","modified":"2026-10-28T02:31:11Z","affected":[{"source":"osv","ecosystem":"Debian:12","package":"u-boot","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2023.01+dfsg-2","2023.01+dfsg-2+deb12u1","2023.01+dfsg-2+deb12u2","2023.01+dfsg-2+deb12u3","2023.04+dfsg-1","2023.04~rc2+dfsg-1","2023.04~rc5+dfsg-1","2023.07+dfsg-1","2023.07~rc4+dfsg-1","2023.07~rc5+dfsg-1","2024.01+dfsg-1","2024.01+dfsg-2","2024.01+dfsg-3","2024.01+dfsg-4","2024.01+dfsg-5","2024.01+dfsg-6","2024.01+dfsg-7","2024.01~rc6+dfsg-1","2024.01~rc6+dfsg-2","2025.01-1","2025.01-2","2025.01-3","2025.01-3.1","2025.01-3.2"]},{"source":"osv","ecosystem":"Debian:13","package":"u-boot","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2025.01-3","2025.01-3+deb13u1","2025.01-3.1","2025.01-3.2"]},{"source":"osv","ecosystem":"Debian:14","package":"u-boot","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2025.01-3","2025.01-3.1","2025.01-3.2"]},{"source":"osv","ecosystem":"Ubuntu:Pro:16.04:LTS","package":"u-boot","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2015.04+dfsg1-2ubuntu1","2015.10+dfsg1-2","2015.10+dfsg1-3","2015.10+dfsg1-4","2016.01+dfsg1-1","2016.01+dfsg1-1ubuntu1","2016.01+dfsg1-2ubuntu1","2016.01+dfsg1-2ubuntu2","2016.01+dfsg1-2ubuntu3","2016.01+dfsg1-2ubuntu5","2016.01+dfsg1-2ubuntu5+esm1","2016.01+dfsg1-2ubuntu5+esm2"]},{"source":"osv","ecosystem":"Ubuntu:Pro:18.04:LTS","package":"u-boot","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2016.03+dfsg1-6ubuntu2","2018.07~rc3+dfsg1-0ubuntu1~18.04.1","2018.07~rc3+dfsg1-0ubuntu2~18.04.1","2018.07~rc3+dfsg1-0ubuntu3~18.04.1","2019.07+dfsg-1ubuntu4~18.04.1","2020.10+dfsg-1ubuntu0~18.04.2","2020.10+dfsg-1ubuntu0~18.04.3","2020.10+dfsg-1ubuntu0~18.04.3+esm1","2020.10+dfsg-1ubuntu0~18.04.3+esm2"]},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"u-boot","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2019.07+dfsg-1ubuntu3","2019.07+dfsg-1ubuntu5","2019.07+dfsg-1ubuntu6","2020.10+dfsg-1ubuntu0~20.04.2","2021.01+dfsg-3ubuntu0~20.04.1","2021.01+dfsg-3ubuntu0~20.04.3","2021.01+dfsg-3ubuntu0~20.04.4","2021.01+dfsg-3ubuntu0~20.04.5","2021.01+dfsg-3ubuntu0~20.04.6","2021.01+dfsg-3ubuntu0~20.04.6+esm1","2021.01+dfsg-3ubuntu0~20.04.6+esm2"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"u-boot","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2021.07+dfsg-0ubuntu8","2021.07+dfsg-0ubuntu9","2021.07+dfsg-0ubuntu10","2022.01+dfsg-2ubuntu1","2022.01+dfsg-2ubuntu2","2022.01+dfsg-2ubuntu2.1","2022.01+dfsg-2ubuntu2.3","2022.01+dfsg-2ubuntu2.4","2022.01+dfsg-2ubuntu2.5","2022.01+dfsg-2ubuntu2.6","2022.01+dfsg-2ubuntu2.7","2022.01+dfsg-2ubuntu2.8","2022.01+dfsg-2ubuntu2.9"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"u-boot-nezha","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2021.09+git20211008.62392d3-0ubuntu1","2022.04+git20220405.7446a472-0ubuntu0.1","2022.04+git20220405.7446a472-0ubuntu0.2","2022.04+git20220405.7446a472-0ubuntu0.3","2022.04+git20220405.7446a472-0ubuntu0.4"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"u-boot","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2023.07+dfsg-1ubuntu2","2024.01+dfsg-1ubuntu1","2024.01+dfsg-1ubuntu2","2024.01+dfsg-1ubuntu3","2024.01+dfsg-1ubuntu4","2024.01+dfsg-1ubuntu5","2024.01+dfsg-1ubuntu5.1","2024.01+dfsg-1ubuntu5.2","2025.01-0ubuntu0.24.04.1","2025.01-0ubuntu0.24.04.2","2025.10-0ubuntu0.24.04.1","2025.10-0ubuntu0.24.04.2","2025.10-0ubuntu0.24.04.3","2025.10-0ubuntu0.24.04.4"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"u-boot-nezha","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2022.10-1089-g528ae9bc6c-0ubuntu2","2024.01~rc1-190-g2e89b706f5-0ubuntu1","2024.01~rc1-190-g2e89b706f5-0ubuntu2","2024.01~rc1-190-g2e89b706f5-0ubuntu2.24.04.2"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"u-boot","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2025.01-1~0ubuntu2","2025.01-3ubuntu1","2025.01-3ubuntu2","2025.01-3ubuntu4","2025.10-0ubuntu0.25.10.1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"u-boot","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2025.10-0ubuntu2","2025.10-0ubuntu3","2025.10-0ubuntu4","2025.10-0ubuntu5","2025.10-0ubuntu6"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"u-boot","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2025.01-3ubuntu4","2025.10-0ubuntu1","2025.10-0ubuntu2","2025.10-0ubuntu2.1","2025.10-0ubuntu2.2"]}],"products":[{"vendor":"denx","product":"u-boot"},{"vendor":"denx software engineering","product":"u-boot"},{"vendor":"u-boot","product":"u-boot"}],"references":[{"url":"https://y637f9qq2x.com/posts/u-boot-tcp-nfs-vulns/","tags":["technical-description","exploit","Third Party Advisory","Exploit","evidence"]},{"url":"https://lists.denx.de/pipermail/u-boot/2026-May/617853.html","tags":["issue-tracking","Mailing List","Third Party Advisory","report"]},{"url":"https://u-boot.org/","tags":["product","Product","web"]},{"url":"https://www.vulncheck.com/advisories/u-boot-rc3-integer-underflow-dos-via-tcp-rx-state-machine","tags":["third-party-advisory","Third Party Advisory","Exploit","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-29008","tags":["advisory"]},{"url":"https://u-boot.org"},{"url":"https://y637f9qq2x.com/posts/u-boot-tcp-nfs-vulns"},{"url":"https://github.com/advisories/GHSA-3qwj-q697-4ppr"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/29xxx/CVE-2026-29008.json","tags":["advisory"]},{"url":"https://github.com/u-boot/u-boot","tags":["package"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-29008","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-29008","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-29008","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-29008","title":"U-Boot 2026.04-rc3 Integer Underflow DoS via tcp_rx_state_machine()","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.","status":"published","published":"2026-07-08T16:14:41.613Z","modified":"2026-07-14T18:39:49.802Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high","assessor":"cna"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-191"],"updated_at":"2026-11-02T14:19:56.284359Z"}],"euvd":[{"id":"EUVD-2026-42332","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.","status":"published","published":"2026-07-08T16:14:41Z","modified":"2026-07-14T18:39:49Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high"}],"updated_at":"2026-11-02T18:19:59.200665Z"}],"ghsa":[{"id":"GHSA-3qwj-q697-4ppr","title":"U-Boot through 2026.04-rc3 contains an integer underflow vulnerability in the...","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.","status":"published","published":"2026-07-08T18:31:37Z","modified":"2026-07-13T21:31:14Z","cvss":[{"version":"4.0","score":8.7,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-191"],"updated_at":"2026-11-02T15:09:26.474991Z"}],"nvd":[{"id":"CVE-2026-29008","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.","status":"published","published":"2026-07-08T17:17:21.047Z","modified":"2026-07-22T18:32:12.677Z","cvss":[{"version":"4.0","score":8.7,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-191"],"updated_at":"2026-11-02T14:12:28.040501Z"}],"osv":[{"id":"CVE-2026-29008","title":"U-Boot 2026.04-rc3 Integer Underflow DoS via tcp_rx_state_machine()","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.","status":"published","published":"2026-07-08T16:14:41.613Z","modified":"2026-10-28T02:31:11.734289829Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high"}],"cwes":["CWE-191"],"updated_at":"2026-11-02T15:45:00.530889Z"},{"id":"DEBIAN-CVE-2026-29008","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.","status":"published","published":"2026-07-08T17:17:21.047Z","modified":"2026-10-01T03:02:34.917834701Z","cvss":[{"version":"4.0","score":8.7,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"}],"updated_at":"2026-11-02T15:45:53.877573Z"},{"id":"UBUNTU-CVE-2026-29008","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.","status":"published","published":"2026-07-08T17:17:00Z","modified":"2026-10-21T23:01:54.331879595Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"},{"version":"4.0","score":8.7,"vector":"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","level":"high"}],"updated_at":"2026-11-02T16:56:11.640778Z"}]}}