{"id":"CVE-2026-98621","title":"net: gue: reject invalid REMCSUM offsets","summary":"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_proc…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= fe881ef11cf0220f118816181930494d484c4883 < 4b9bc21b2396c396d88dd909caaf73d5be6ff593","Linux >= fe881ef11cf0220f118816181930494d484c4883 < 43efb1f997e976f386aa89716f55870cd2cff9ad","Linux >= fe881ef11cf0220f118816181930494d484c4883 < 1eeec0c51fd5598da44080ed96bbd9880021c28b","Linux >= fe881ef11cf0220f118816181930494d484c4883 < 1d664be4ca49d1696e85239236f4988dfc4653c3","Linux >= fe881ef11cf0220f118816181930494d484c4883 < 97f907203321eee2cc9132d5c9eb47698fb41d35","Linux >= fe881ef11cf0220f118816181930494d484c4883 < 40aeafbcbc7bc4018e8f74bbbb4d29ed8846f57f","Linux >= fe881ef11cf0220f118816181930494d484c4883 < c20f755338ca234e523dfc943719f194dfc1f903","Linux >= fe881ef11cf0220f118816181930494d484c4883 < 2566866fc30965d915d0b52b5c3323b362619f0e","Linux 4.0"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:19:41.211Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98621","references":[{"url":"https://git.kernel.org/stable/c/4b9bc21b2396c396d88dd909caaf73d5be6ff593"},{"url":"https://git.kernel.org/stable/c/43efb1f997e976f386aa89716f55870cd2cff9ad"},{"url":"https://git.kernel.org/stable/c/1eeec0c51fd5598da44080ed96bbd9880021c28b"},{"url":"https://git.kernel.org/stable/c/1d664be4ca49d1696e85239236f4988dfc4653c3"},{"url":"https://git.kernel.org/stable/c/97f907203321eee2cc9132d5c9eb47698fb41d35"},{"url":"https://git.kernel.org/stable/c/40aeafbcbc7bc4018e8f74bbbb4d29ed8846f57f"},{"url":"https://git.kernel.org/stable/c/c20f755338ca234e523dfc943719f194dfc1f903"},{"url":"https://git.kernel.org/stable/c/2566866fc30965d915d0b52b5c3323b362619f0e"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T15:45:12.239Z","slug":"CVE-2026-98621","body":"## Overview\n\nIn 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->csum_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.\n\n## Affected\n\n- `Linux >= fe881ef11cf0220f118816181930494d484c4883 < 4b9bc21b2396c396d88dd909caaf73d5be6ff593`\n- `Linux >= fe881ef11cf0220f118816181930494d484c4883 < 43efb1f997e976f386aa89716f55870cd2cff9ad`\n- `Linux >= fe881ef11cf0220f118816181930494d484c4883 < 1eeec0c51fd5598da44080ed96bbd9880021c28b`\n- `Linux >= fe881ef11cf0220f118816181930494d484c4883 < 1d664be4ca49d1696e85239236f4988dfc4653c3`\n- `Linux >= fe881ef11cf0220f118816181930494d484c4883 < 97f907203321eee2cc9132d5c9eb47698fb41d35`\n- `Linux >= fe881ef11cf0220f118816181930494d484c4883 < 40aeafbcbc7bc4018e8f74bbbb4d29ed8846f57f`\n- `Linux >= fe881ef11cf0220f118816181930494d484c4883 < c20f755338ca234e523dfc943719f194dfc1f903`\n- `Linux >= fe881ef11cf0220f118816181930494d484c4883 < 2566866fc30965d915d0b52b5c3323b362619f0e`\n- `Linux 4.0`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}