CVE-2026-31469 - Vulnerability Details

- virtio_net: Fix UAF on dst_ops when IFF_XMIT_DST_RELEASE is cleared and napi_tx is false

Description

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

Published: 2026-04-22

Score: 7.0 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

A use‑after‑free occurs when the virtio_net driver runs with napi_tx disabled and the IFF_XMIT_DST_RELEASE flag is cleared while transmitted packets remain in the virtio ring; destroying the network namespace frees the underlying dst_ops structure, causing a subsequent packet transmission to dereference a freed pointer and trigger a kernel paging request. The flaw is a classic Use‑After‑Free (CWE‑416) that results in an unconditional crash and denial of service rather than arbitrary code execution.

Affected Systems

The vulnerability affects the Linux kernel, specifically the virtio_net driver module. Version information is not enumerated in the advisory; however, the issue was confirmed against a 7.0.0‑rc1 kernel instance and is likely present in all kernels that have not applied the commit that introduces skb_dst_drop in start_xmit.

Risk and Exploitability

The CVSS score is not provided and EPSS is unavailable; the vulnerability is not listed in CISA KEV. Exploitation requires a local user with the ability to create and delete network namespaces or manipulate netlink qdisc settings, which effectively grants root or at least kernel‑module capability. Given that the impact is a forced kernel panic, the risk is high for affected systems, but the vector is limited to privileged locals. In practice, operators should assess whether they run untrusted software with netns or tc access before applying this fix.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`f2fc6a54585a1be6669613a31fbaba2ecbadcd36`	affected	< be0e63f3b97bbaf453c542e8a15ba2a536e2ac01
`f2fc6a54585a1be6669613a31fbaba2ecbadcd36`	affected	< c1ec36cb3768574b916f20d2d7415fd14fa1bf12
`f2fc6a54585a1be6669613a31fbaba2ecbadcd36`	affected	< 8a4790850e710fd6771e4d2112168ed1dd6c0e54
`f2fc6a54585a1be6669613a31fbaba2ecbadcd36`	affected	< fedd2e1630cac920844997227ccbe7b26a76375a
`f2fc6a54585a1be6669613a31fbaba2ecbadcd36`	affected	< f04733c4dc40c43899c3d1c97afbae5831a3770f
`f2fc6a54585a1be6669613a31fbaba2ecbadcd36`	affected	< 9a18629f2525781f0f3dda7be72b204e4cf77d08
`f2fc6a54585a1be6669613a31fbaba2ecbadcd36`	affected	< 63d45077b97bb0e0fe0c75931acbbca7a47af141
`f2fc6a54585a1be6669613a31fbaba2ecbadcd36`	affected	< ba8bda9a0896746053aa97ac6c3e08168729172c

Linux

affected

Version	Status	Constraints
`2.6.26`	affected	—
`0`	unaffected	< 2.6.26
`5.10.253`	unaffected	≤ 5.10.*
`5.15.203`	unaffected	≤ 5.15.*
`6.1.168`	unaffected	≤ 6.1.*
`6.6.131`	unaffected	≤ 6.6.*
`6.12.80`	unaffected	≤ 6.12.*
`6.18.21`	unaffected	≤ 6.18.*
`6.19.11`	unaffected	≤ 6.19.*
`7.0`	unaffected	≤ *

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[f2fc6a54585a1be6669613a31fbaba2ecbadcd36,be0e63f3b97bbaf453c542e8a15ba2a536e2ac01)`	affected	code_commit	—
`[f2fc6a54585a1be6669613a31fbaba2ecbadcd36,c1ec36cb3768574b916f20d2d7415fd14fa1bf12)`	affected	code_commit	—
`[f2fc6a54585a1be6669613a31fbaba2ecbadcd36,8a4790850e710fd6771e4d2112168ed1dd6c0e54)`	affected	code_commit	—
`[f2fc6a54585a1be6669613a31fbaba2ecbadcd36,fedd2e1630cac920844997227ccbe7b26a76375a)`	affected	code_commit	—
`[f2fc6a54585a1be6669613a31fbaba2ecbadcd36,f04733c4dc40c43899c3d1c97afbae5831a3770f)`	affected	code_commit	—
`[f2fc6a54585a1be6669613a31fbaba2ecbadcd36,9a18629f2525781f0f3dda7be72b204e4cf77d08)`	affected	code_commit	—
`[f2fc6a54585a1be6669613a31fbaba2ecbadcd36,63d45077b97bb0e0fe0c75931acbbca7a47af141)`	affected	code_commit	—
`[f2fc6a54585a1be6669613a31fbaba2ecbadcd36,ba8bda9a0896746053aa97ac6c3e08168729172c)`	affected	code_commit	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`2.6.26`	affected	semver	—
`[0,2.6.26)`	unaffected	semver	—
`[5.10.253,5.11.0)`	unaffected	semver	—
`[5.15.203,5.16.0)`	unaffected	semver	—
`[6.1.168,6.2.0)`	unaffected	semver	—
`[6.6.131,6.7.0)`	unaffected	semver	—
`[6.12.80,6.13.0)`	unaffected	semver	—
`[6.18.21,6.19.0)`	unaffected	semver	—
`[6.19.11,6.20.0)`	unaffected	semver	—
`[7.0,*]`	unaffected	generic	—

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Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

Apply the Linux kernel update that includes the commit referenced in the advisory (e.g., update to any kernel version that contains the skb_dst_drop addition to virtio_net start_xmit).
If immediate kernel update is not possible, refrain from destroying network namespaces while packets may still be queued in virtio_net and limit manipulation of IFF_XMIT_DST_RELEASE and route filter qdiscs.
After upgrading, rebuild any custom kernel modules and verify that the virtio_net module reflects the updated commit hash.

Generated by OpenCVE AI on April 22, 2026 at 19:00 UTC.

Tracking

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Advisories

No advisories yet.

No CVSS v4.0

Attack Vector Local

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00024.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/63d45077b97bb0e0fe0c75931acbbca7a47af141
https://git.kernel.org/stable/c/8a4790850e710fd6771e4d2112168ed1dd6c0e54
https://git.kernel.org/stable/c/9a18629f2525781f0f3dda7be72b204e4cf77d08
https://git.kernel.org/stable/c/ba8bda9a0896746053aa97ac6c3e08168729172c
https://git.kernel.org/stable/c/be0e63f3b97bbaf453c542e8a15ba2a536e2ac01
https://git.kernel.org/stable/c/c1ec36cb3768574b916f20d2d7415fd14fa1bf12
https://git.kernel.org/stable/c/f04733c4dc40c43899c3d1c97afbae5831a3770f
https://git.kernel.org/stable/c/fedd2e1630cac920844997227ccbe7b26a76375a
https://lore.kernel.org/linux-cve-announce/2026042254-CVE-2026-31469-65d8@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2026-31469
https://www.cve.org/CVERecord?id=CVE-2026-31469

History

Thu, 23 Apr 2026 00:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-911
References		https://lore.kernel.org/linux-cve-announce/2026042254-CVE-2026-31469-65d8@gregkh/T https://nvd.nist.gov/vuln/detail/CVE-2026-31469 https://www.cve.org/CVERecord?id=CVE-2026-31469
Metrics	threat_severity `None`	cvssV3_1 `{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}` threat_severity `Moderate`

Wed, 22 Apr 2026 14:15:00 +0000

Type	Values Removed	Values Added
Description		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
Title		virtio_net: Fix UAF on dst_ops when IFF_XMIT_DST_RELEASE is cleared and napi_tx is false
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/63d45077b97bb0e0fe0c75931acbbca7a47af141 https://git.kernel.org/stable/c/8a4790850e710fd6771e4d2112168ed1dd6c0e54 https://git.kernel.org/stable/c/9a18629f2525781f0f3dda7be72b204e4cf77d08 https://git.kernel.org/stable/c/ba8bda9a0896746053aa97ac6c3e08168729172c https://git.kernel.org/stable/c/be0e63f3b97bbaf453c542e8a15ba2a536e2ac01 https://git.kernel.org/stable/c/c1ec36cb3768574b916f20d2d7415fd14fa1bf12 https://git.kernel.org/stable/c/f04733c4dc40c43899c3d1c97afbae5831a3770f https://git.kernel.org/stable/c/fedd2e1630cac920844997227ccbe7b26a76375a

Subscriptions

Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-04-22T13:53:58.266Z

Updated: 2026-04-22T13:53:58.266Z

Reserved: 2026-03-09T15:48:24.097Z

Link: CVE-2026-31469

Vulnrichment

No data.

NVD

Status : Awaiting Analysis

Published: 2026-04-22T14:16:43.260

Modified: 2026-04-23T16:17:41.280

Link: CVE-2026-31469

Redhat

Severity : Moderate

Publid Date: 2026-04-22T00:00:00Z

Links: CVE-2026-31469 - Bugzilla

OpenCVE Enrichment

Updated: 2026-04-22T19:15:24Z

Weaknesses

CWE-911

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Local

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

Subscriptions

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