FKIE_CVE-2026-31469
Vulnerability from fkie_nvd - Published: 2026-04-22 14:16 - Updated: 2026-07-14 13:18
Severity
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
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 | |
| linux | linux_kernel | 7.0 |
{
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{
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],
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},
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"version": "0",
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},
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},
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"version": "5.15.203",
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},
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"version": "6.1.168",
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},
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"version": "6.12.80",
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},
{
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},
{
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},
{
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}
]
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],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
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{
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"product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
"vendor": "Siemens",
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"version": "V3.1.6",
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]
},
{
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"vendor": "Siemens",
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{
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"vendor": "Siemens",
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{
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"vendor": "Siemens",
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},
{
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"vendor": "Siemens",
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{
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{
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"vendor": "Siemens",
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"version": "V3.1.6",
"versionType": "custom"
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},
{
"defaultStatus": "unknown",
"product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
"vendor": "Siemens",
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"status": "affected",
"version": "V3.1.5",
"versionType": "custom"
}
]
},
{
"defaultStatus": "unknown",
"product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
"vendor": "Siemens",
"versions": [
{
"lessThan": "*",
"status": "affected",
"version": "V3.1.6",
"versionType": "custom"
}
]
},
{
"defaultStatus": "unknown",
"product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
"vendor": "Siemens",
"versions": [
{
"lessThan": "*",
"status": "affected",
"version": "V3.1.5",
"versionType": "custom"
}
]
}
],
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
}
],
"configurations": [
{
"nodes": [
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],
"cveTags": [],
"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"
}
],
"id": "CVE-2026-31469",
"lastModified": "2026-07-14T13:18:42.810",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-04-22T14:16:43.260",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/63d45077b97bb0e0fe0c75931acbbca7a47af141"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
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],
"url": "https://git.kernel.org/stable/c/8a4790850e710fd6771e4d2112168ed1dd6c0e54"
},
{
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{
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},
{
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},
{
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"tags": [
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"url": "https://git.kernel.org/stable/c/c1ec36cb3768574b916f20d2d7415fd14fa1bf12"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
"Patch"
],
"url": "https://git.kernel.org/stable/c/f04733c4dc40c43899c3d1c97afbae5831a3770f"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
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],
"url": "https://git.kernel.org/stable/c/fedd2e1630cac920844997227ccbe7b26a76375a"
},
{
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
},
{
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Modified",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-416"
}
],
"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- 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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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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