CVE-2026-31469 (GCVE-0-2026-31469)
Vulnerability from cvelistv5 – Published: 2026-04-22 13:53 – Updated: 2026-04-27 14:03
VLAI?
Title
virtio_net: Fix UAF on dst_ops when IFF_XMIT_DST_RELEASE is cleared and napi_tx is false
Summary
In the Linux kernel, the following vulnerability has been resolved:
virtio_net: Fix UAF on dst_ops when IFF_XMIT_DST_RELEASE is cleared and napi_tx is false
A UAF issue occurs when the virtio_net driver is configured with napi_tx=N
and the device's IFF_XMIT_DST_RELEASE flag is cleared
(e.g., during the configuration of tc route filter rules).
When IFF_XMIT_DST_RELEASE is removed from the net_device, the network stack
expects the driver to hold the reference to skb->dst until the packet
is fully transmitted and freed. In virtio_net with napi_tx=N,
skbs may remain in the virtio transmit ring for an extended period.
If the network namespace is destroyed while these skbs are still pending,
the corresponding dst_ops structure has freed. When a subsequent packet
is transmitted, free_old_xmit() is triggered to clean up old skbs.
It then calls dst_release() on the skb associated with the stale dst_entry.
Since the dst_ops (referenced by the dst_entry) has already been freed,
a UAF kernel paging request occurs.
fix it by adds skb_dst_drop(skb) in start_xmit to explicitly release
the dst reference before the skb is queued in virtio_net.
Call Trace:
Unable to handle kernel paging request at virtual address ffff80007e150000
CPU: 2 UID: 0 PID: 6236 Comm: ping Kdump: loaded Not tainted 7.0.0-rc1+ #6 PREEMPT
...
percpu_counter_add_batch+0x3c/0x158 lib/percpu_counter.c:98 (P)
dst_release+0xe0/0x110 net/core/dst.c:177
skb_release_head_state+0xe8/0x108 net/core/skbuff.c:1177
sk_skb_reason_drop+0x54/0x2d8 net/core/skbuff.c:1255
dev_kfree_skb_any_reason+0x64/0x78 net/core/dev.c:3469
napi_consume_skb+0x1c4/0x3a0 net/core/skbuff.c:1527
__free_old_xmit+0x164/0x230 drivers/net/virtio_net.c:611 [virtio_net]
free_old_xmit drivers/net/virtio_net.c:1081 [virtio_net]
start_xmit+0x7c/0x530 drivers/net/virtio_net.c:3329 [virtio_net]
...
Reproduction Steps:
NETDEV="enp3s0"
config_qdisc_route_filter() {
tc qdisc del dev $NETDEV root
tc qdisc add dev $NETDEV root handle 1: prio
tc filter add dev $NETDEV parent 1:0 \
protocol ip prio 100 route to 100 flowid 1:1
ip route add 192.168.1.100/32 dev $NETDEV realm 100
}
test_ns() {
ip netns add testns
ip link set $NETDEV netns testns
ip netns exec testns ifconfig $NETDEV 10.0.32.46/24
ip netns exec testns ping -c 1 10.0.32.1
ip netns del testns
}
config_qdisc_route_filter
test_ns
sleep 2
test_ns
Severity ?
7.8 (High)
Assigner
References
Impacted products
| Vendor | Product | Version | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux |
Affected:
f2fc6a54585a1be6669613a31fbaba2ecbadcd36 , < be0e63f3b97bbaf453c542e8a15ba2a536e2ac01
(git)
Affected: f2fc6a54585a1be6669613a31fbaba2ecbadcd36 , < c1ec36cb3768574b916f20d2d7415fd14fa1bf12 (git) Affected: f2fc6a54585a1be6669613a31fbaba2ecbadcd36 , < 8a4790850e710fd6771e4d2112168ed1dd6c0e54 (git) Affected: f2fc6a54585a1be6669613a31fbaba2ecbadcd36 , < fedd2e1630cac920844997227ccbe7b26a76375a (git) Affected: f2fc6a54585a1be6669613a31fbaba2ecbadcd36 , < f04733c4dc40c43899c3d1c97afbae5831a3770f (git) Affected: f2fc6a54585a1be6669613a31fbaba2ecbadcd36 , < 9a18629f2525781f0f3dda7be72b204e4cf77d08 (git) Affected: f2fc6a54585a1be6669613a31fbaba2ecbadcd36 , < 63d45077b97bb0e0fe0c75931acbbca7a47af141 (git) Affected: f2fc6a54585a1be6669613a31fbaba2ecbadcd36 , < ba8bda9a0896746053aa97ac6c3e08168729172c (git) |
|||||||
|
|||||||||
{
"containers": {
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"product": "Linux",
"programFiles": [
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"versions": [
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"version": "2.6.26"
},
{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "5.10.253",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "5.15.203",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.168",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.6.131",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.80",
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},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.21",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.19.*",
"status": "unaffected",
"version": "6.19.11",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.0",
"versionType": "original_commit_for_fix"
}
]
}
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvirtio_net: Fix UAF on dst_ops when IFF_XMIT_DST_RELEASE is cleared and napi_tx is false\n\nA UAF issue occurs when the virtio_net driver is configured with napi_tx=N\nand the device\u0027s IFF_XMIT_DST_RELEASE flag is cleared\n(e.g., during the configuration of tc route filter rules).\n\nWhen IFF_XMIT_DST_RELEASE is removed from the net_device, the network stack\nexpects the driver to hold the reference to skb-\u003edst until the packet\nis fully transmitted and freed. In virtio_net with napi_tx=N,\nskbs may remain in the virtio transmit ring for an extended period.\n\nIf the network namespace is destroyed while these skbs are still pending,\nthe corresponding dst_ops structure has freed. When a subsequent packet\nis transmitted, free_old_xmit() is triggered to clean up old skbs.\nIt then calls dst_release() on the skb associated with the stale dst_entry.\nSince the dst_ops (referenced by the dst_entry) has already been freed,\na UAF kernel paging request occurs.\n\nfix it by adds skb_dst_drop(skb) in start_xmit to explicitly release\nthe dst reference before the skb is queued in virtio_net.\n\nCall Trace:\n Unable to handle kernel paging request at virtual address ffff80007e150000\n CPU: 2 UID: 0 PID: 6236 Comm: ping Kdump: loaded Not tainted 7.0.0-rc1+ #6 PREEMPT\n ...\n percpu_counter_add_batch+0x3c/0x158 lib/percpu_counter.c:98 (P)\n dst_release+0xe0/0x110 net/core/dst.c:177\n skb_release_head_state+0xe8/0x108 net/core/skbuff.c:1177\n sk_skb_reason_drop+0x54/0x2d8 net/core/skbuff.c:1255\n dev_kfree_skb_any_reason+0x64/0x78 net/core/dev.c:3469\n napi_consume_skb+0x1c4/0x3a0 net/core/skbuff.c:1527\n __free_old_xmit+0x164/0x230 drivers/net/virtio_net.c:611 [virtio_net]\n free_old_xmit drivers/net/virtio_net.c:1081 [virtio_net]\n start_xmit+0x7c/0x530 drivers/net/virtio_net.c:3329 [virtio_net]\n ...\n\nReproduction Steps:\nNETDEV=\"enp3s0\"\n\nconfig_qdisc_route_filter() {\n tc qdisc del dev $NETDEV root\n tc qdisc add dev $NETDEV root handle 1: prio\n tc filter add dev $NETDEV parent 1:0 \\\n\tprotocol ip prio 100 route to 100 flowid 1:1\n ip route add 192.168.1.100/32 dev $NETDEV realm 100\n}\n\ntest_ns() {\n ip netns add testns\n ip link set $NETDEV netns testns\n ip netns exec testns ifconfig $NETDEV 10.0.32.46/24\n ip netns exec testns ping -c 1 10.0.32.1\n ip netns del testns\n}\n\nconfig_qdisc_route_filter\n\ntest_ns\nsleep 2\ntest_ns"
}
],
"metrics": [
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"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-04-27T14:03:23.780Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
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"url": "https://git.kernel.org/stable/c/be0e63f3b97bbaf453c542e8a15ba2a536e2ac01"
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"url": "https://git.kernel.org/stable/c/c1ec36cb3768574b916f20d2d7415fd14fa1bf12"
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"url": "https://git.kernel.org/stable/c/8a4790850e710fd6771e4d2112168ed1dd6c0e54"
},
{
"url": "https://git.kernel.org/stable/c/fedd2e1630cac920844997227ccbe7b26a76375a"
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"url": "https://git.kernel.org/stable/c/f04733c4dc40c43899c3d1c97afbae5831a3770f"
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{
"url": "https://git.kernel.org/stable/c/9a18629f2525781f0f3dda7be72b204e4cf77d08"
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{
"url": "https://git.kernel.org/stable/c/63d45077b97bb0e0fe0c75931acbbca7a47af141"
},
{
"url": "https://git.kernel.org/stable/c/ba8bda9a0896746053aa97ac6c3e08168729172c"
}
],
"title": "virtio_net: Fix UAF on dst_ops when IFF_XMIT_DST_RELEASE is cleared and napi_tx is false",
"x_generator": {
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}
}
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"cveMetadata": {
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"assignerShortName": "Linux",
"cveId": "CVE-2026-31469",
"datePublished": "2026-04-22T13:53:58.266Z",
"dateReserved": "2026-03-09T15:48:24.097Z",
"dateUpdated": "2026-04-27T14:03:23.780Z",
"state": "PUBLISHED"
},
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"dataVersion": "5.2",
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"epss": {
"cve": "CVE-2026-31469",
"date": "2026-04-27",
"epss": "0.00024",
"percentile": "0.06785"
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}
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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