{"id":"AZL-112862","summary":"CVE-2026-99282 affecting package kernel 6.6.161.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_teql: fix use-after-free on lower qdisc drop\n\nThe issue: teql_master_xmit() tests the slave's ndo_start_xmit() return\nvalue against NETDEV_TX_OK alone. A slave that consumes the skb but\nreturns an error code (rc \u003c NET_XMIT_MASK, e.g. NET_XMIT_DROP) is treated\nas if the skb were still owned, so the loop restores skb-\u003edev and calls\n__skb_pull() on it. A VLAN slave returns the result of dev_queue_xmit()\nfrom its ndo_start_xmit() (propagated since cbbef5e18307), and when the\nlower qdisc drops the packet that value is NET_XMIT_DROP after the skb\nhas been freed, giving a use-after-free in teql_master_xmit().\n\nThe Fix: test for consumption with dev_xmit_complete(), which accepts\nNETDEV_TX_OK and every rc \u003c NET_XMIT_MASK, matching other callers that\nneed to distinguish consumed results from busy. Only NETDEV_TX_OK keeps\nthe packet counted in tx_packets/tx_bytes and advances the slave; a\nconsumed result that is neither a success nor NET_XMIT_CN ends the\nattempt and is charged to tx_dropped, so lower-qdisc drops are no longer\nreported as good transmits. NET_XMIT_CN is counted like success because\nit can accompany acceptance of the current packet: pfifo_head_drop drops\nthe old head, enqueues the current skb and returns NET_XMIT_CN.\n\nConditions to recreate the bug:\nWith CONFIG_NET_SCH_TEQL,\nCONFIG_VLAN_8021Q and CONFIG_DUMMY enabled, add lkrdummy0 (dummy) and\nlkrvlan0 (VLAN id 37 on lkrdummy0); set a pfifo limit 0 root on lkrdummy0\nand a teql0 root on lkrvlan0; bring teql0 up with an address and send one\nUDP packet to it. The VLAN xmit returns NET_XMIT_DROP from the lower\nqdisc while holding a freed skb.","modified":"2026-11-08T14:16:22.494346479Z","published":"2026-11-07T14:17:03Z","upstream":["CVE-2026-99282"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99282"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.161.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-112862.json"}}],"schema_version":"1.9.2"}