CVE-2026-99282
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_teql: fix use-after-free on lower qdisc drop The issue: teql_master_xmit() tests the slave's ndo_start_xmit() return value against NETDEV_TX_OK alone. A slave that consumes the skb but returns an error code (rc < NET_XMIT_MASK, e.g. NET_XMIT_DROP) is treated as if the skb were still owned, so the loop restores skb->dev and calls __skb_pull() on it. A VLAN slave returns the result of dev_queue_xmit() from its ndo_start_xmit() (propagated since cbbef5e18307), and when the lower qdisc drops the packet that value is NET_XMIT_DROP after the skb has been freed, giving a use-after-free in teql_master_xmit(). The Fix: test for consumption with dev_xmit_complete(), which accepts NETDEV_TX_OK and every rc < NET_XMIT_MASK, matching other callers that need to distinguish consumed results from busy. Only NETDEV_TX_OK keeps the packet counted in tx_packets/tx_bytes and advances the slave; a consumed result that is neither a success nor NET_XMIT_CN ends the attempt and is charged to tx_dropped, so lower-qdisc drops are no longer reported as good transmits. NET_XMIT_CN is counted like success because it can accompany acceptance of the current packet: pfifo_head_drop drops the old head, enqueues the current skb and returns NET_XMIT_CN. Conditions to recreate the bug: With CONFIG_NET_SCH_TEQL, CONFIG_VLAN_8021Q and CONFIG_DUMMY enabled, add lkrdummy0 (dummy) and lkrvlan0 (VLAN id 37 on lkrdummy0); set a pfifo limit 0 root on lkrdummy0 and a teql0 root on lkrvlan0; bring teql0 up with an address and send one UDP packet to it. The VLAN xmit returns NET_XMIT_DROP from the lower qdisc while holding a freed skb.
View original CVE JSON
{
"id": "CVE-2026-99282",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-11-07T14:17:03.940",
"lastModified": "2026-11-07T14:17:03.940",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "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 < NET_XMIT_MASK, e.g. NET_XMIT_DROP) is treated\nas if the skb were still owned, so the loop restores skb->dev 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 < 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."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"net/sched/sch_teql.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "572a9d7b6fc7f20f573664063324c086be310c42",
"lessThan": "fc55d92ae6a4b2e7d062cad6d4c67f6b061d9cde",
"versionType": "git",
"status": "affected"
},
{
"version": "572a9d7b6fc7f20f573664063324c086be310c42",
"lessThan": "2702ae318630787c640ec0d0403ffd9d95c43e9e",
"versionType": "git",
"status": "affected"
},
{
"version": "572a9d7b6fc7f20f573664063324c086be310c42",
"lessThan": "782d6bb8f9b8e9d8591181662222bf74cd3ecf79",
"versionType": "git",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"net/sched/sch_teql.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "2.6.33",
"status": "affected"
},
{
"version": "0",
"lessThan": "2.6.33",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.61",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3.2",
"lessThanOrEqual": "7.3.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.4-rc1",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {},
"references": [
{
"url": "https://git.kernel.org/stable/c/2702ae318630787c640ec0d0403ffd9d95c43e9e",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/782d6bb8f9b8e9d8591181662222bf74cd3ecf79",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/fc55d92ae6a4b2e7d062cad6d4c67f6b061d9cde",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
]
}