{"id":"CVE-2026-99088","aliases":[],"title":"net: openvswitch: validate transport header presence in set_ipv6_addr","titleSource":"Linux","descriptionSource":"Linux","products":[{"vendor":"Linux","name":"Linux","platforms":[],"versions":[{"version":"3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b","status":"affected","lessThan":"b7b80d204abdc258006f9e17c92b363ab13bb599","versionType":"git"},{"version":"3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b","status":"affected","lessThan":"6774af7cd17be8f0d0f70de3a749d381b4f2e9da","versionType":"git"},{"version":"3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b","status":"affected","lessThan":"2594795fd832f0253826d64ff8976b8ff5fbfe9f","versionType":"git"},{"version":"3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b","status":"affected","lessThan":"6b8897ba0733f88f0360ea48a970f373f9142de0","versionType":"git"},{"version":"3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b","status":"affected","lessThan":"3c6a4b11330fe424557538a98fca9f0a4c5bf313","versionType":"git"}],"defaultStatus":"unaffected","source":"Linux","url":"https://www.cve.org/CVERecord?id=CVE-2026-99088"},{"vendor":"Linux","name":"Linux","platforms":[],"versions":[{"version":"3.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.8","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.113","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.11","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"defaultStatus":"affected","source":"Linux","url":"https://www.cve.org/CVERecord?id=CVE-2026-99088"}],"remediation":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: openvswitch: validate transport header presence in set_ipv6_addr\n\nWhen executing IPv6 address rewrite actions on IPv6 fragments,\nset_ipv6_addr() calls update_ipv6_checksum(). If parse_ipv6hdr()\nprocesses a non-first IPv6 fragment, it sets key->ip.proto to\nNEXTHDR_FRAGMENT and returns early without calling\nskb_set_transport_header().\n\nupdate_ipv6_checksum() unconditionally evaluates skb_transport_offset()\non entry before checking l4_proto.  Because skb->transport_header is\nuninitialized, this triggers a warning under CONFIG_DEBUG_NET=y although\nit is completely harmless.\n\nFix this by returning early in update_ipv6_checksum() if l4_proto is\nNEXTHDR_FRAGMENT. This avoids reading the uninitialized transport offset\nfor fragments while preserving the debug warning for any other protocol\nwhere the transport header is unexpectedly missing.\n\nSee the syzbot trace:\n\n!skb_transport_header_was_set(skb)\nWARNING: ./include/linux/skbuff.h:3075 at skb_transport_header include/linux/skbuff.h:3075 [inline], CPU#1: syz-executor463/5635\nWARNING: ./include/linux/skbuff.h:3075 at skb_transport_offset include/linux/skbuff.h:3250 [inline], CPU#1: syz-executor463/5635\nWARNING: ./include/linux/skbuff.h:3075 at update_ipv6_checksum net/openvswitch/actions.c:361 [inline], CPU#1: syz-executor463/5635\nWARNING: ./include/linux/skbuff.h:3075 at set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399, CPU#1: syz-executor463/5635\n[...]\nRIP: 0010:skb_transport_header include/linux/skbuff.h:3075 [inline]\nRIP: 0010:skb_transport_offset include/linux/skbuff.h:3250 [inline]\nRIP: 0010:update_ipv6_checksum net/openvswitch/actions.c:361 [inline]\nRIP: 0010:set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399\n[...]\nCall Trace:\n <TASK>\n set_ipv6 net/openvswitch/actions.c:531 [inline]\n do_execute_actions+0x557e/0x8600 net/openvswitch/actions.c:1366\n ovs_execute_actions+0xde/0x520 net/openvswitch/actions.c:1592\n ovs_packet_cmd_execute+0xb4f/0xf10 net/openvswitch/datapath.c:705\n genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114\n genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209\n netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2572\n genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218\n netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1361\n netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1916\n sock_sendmsg_nosec+0x14e/0x190 net/socket.c:800","severity":"unknown","score":null,"published":"2026-10-26T14:51:58.460Z","modified":"2026-10-26T14:51:58.460Z","withdrawn":false,"knownExploited":false,"affected":[],"references":["https://git.kernel.org/stable/c/b7b80d204abdc258006f9e17c92b363ab13bb599","https://git.kernel.org/stable/c/6774af7cd17be8f0d0f70de3a749d381b4f2e9da","https://git.kernel.org/stable/c/2594795fd832f0253826d64ff8976b8ff5fbfe9f","https://git.kernel.org/stable/c/6b8897ba0733f88f0360ea48a970f373f9142de0","https://git.kernel.org/stable/c/3c6a4b11330fe424557538a98fca9f0a4c5bf313"],"sources":[{"name":"CVE","id":"CVE-2026-99088","modified":"2026-10-26T14:51:58.460Z","url":"https://www.cve.org/CVERecord?id=CVE-2026-99088"}],"assessments":[],"sourceAffected":[],"kev":{"status":"not-listed","checkedAt":"2026-10-29T02:15:32.063Z"},"coverage":[{"source":"NVD","status":"not-checked"},{"source":"GHSA","status":"not-checked"},{"source":"EUVD","status":"not-checked"},{"source":"EPSS","status":"not-checked"}],"evidence":[]}