{"id":"CVE-2026-98621","summary":"net: gue: reject invalid REMCSUM offsets","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: gue: reject invalid REMCSUM offsets\n\nThe REMCSUM option carries an absolute checksum start and checksum field\noffset. gue_remcsum() passes them to skb_remcsum_process(), whose\npartial path stores offset - start in the u16 skb-\u003ecsum_offset variable.\nIf offset is less than start, this underflows.\n\nA forwarded packet can retain CHECKSUM_PARTIAL and reach a NETIF_F_HW_CSUM\ndriver which trusts the metadata, leading skb_copy_and_csum_dev() to write\ntwo bytes about 64 KiB beyond the destination buffer.\n\nReject reversed tuples in validate_gue_flags(), after the existing length\nvalidation, so all GUE parsers enforce the ordering in one place.","modified":"2026-10-19T02:47:00.170613123Z","published":"2026-10-18T15:19:41.211Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98621.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1d664be4ca49d1696e85239236f4988dfc4653c3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1eeec0c51fd5598da44080ed96bbd9880021c28b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2566866fc30965d915d0b52b5c3323b362619f0e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/40aeafbcbc7bc4018e8f74bbbb4d29ed8846f57f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/43efb1f997e976f386aa89716f55870cd2cff9ad"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4b9bc21b2396c396d88dd909caaf73d5be6ff593"},{"type":"WEB","url":"https://git.kernel.org/stable/c/97f907203321eee2cc9132d5c9eb47698fb41d35"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c20f755338ca234e523dfc943719f194dfc1f903"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98621.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98621"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"fe881ef11cf0220f118816181930494d484c4883"},{"fixed":"4b9bc21b2396c396d88dd909caaf73d5be6ff593"},{"fixed":"43efb1f997e976f386aa89716f55870cd2cff9ad"},{"fixed":"1eeec0c51fd5598da44080ed96bbd9880021c28b"},{"fixed":"1d664be4ca49d1696e85239236f4988dfc4653c3"},{"fixed":"97f907203321eee2cc9132d5c9eb47698fb41d35"},{"fixed":"40aeafbcbc7bc4018e8f74bbbb4d29ed8846f57f"},{"fixed":"c20f755338ca234e523dfc943719f194dfc1f903"},{"fixed":"2566866fc30965d915d0b52b5c3323b362619f0e"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98621.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.0.0"},{"fixed":"5.10.271"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.222"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.189"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.158"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.112"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.55"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98621.json"}}],"schema_version":"1.9.0"}