Linux: Use After Free
CVE-2026-31469 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions be0e63f3b97bbaf453c542e8a15ba2a536e2ac01, c1ec36cb3768574b916f20d2d7415fd14fa1bf12, 8a4790850e710fd6771e4d2112168ed1dd6c0e54 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.14% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to be0e63f3b97bbaf453c542e8a15ba2a536e2ac01 or c1ec36cb3768574b916f20d2d7415fd14fa1bf12 or 8a4790850e710fd6771e4d2112168ed1dd6c0e54 or fedd2e1630cac920844997227ccbe7b26a76375a, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.253 or 5.15.203 or 6.1.168 or 6.6.131, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | f2fc6a54585a1be6669613a31fbaba2ecbadcd36 up to, but not including, be0e63f3b97bbaf453c542e8a15ba2a536e2ac01; f2fc6a54585a1be6669613a31fbaba2ecbadcd36 up to, but not including, c1ec36cb3768574b916f20d2d7415fd14fa1bf12; f2fc6a54585a1be6669613a31fbaba2ecbadcd36 up to, but not including, 8a4790850e710fd6771e4d2112168ed1dd6c0e54; f2fc6a54585a1be6669613a31fbaba2ecbadcd36 up to, but not including, fedd2e1630cac920844997227ccbe7b26a76375a; f2fc6a54585a1be6669613a31fbaba2ecbadcd36 up to, but not including, f04733c4dc40c43899c3d1c97afbae5831a3770f; f2fc6a54585a1be6669613a31fbaba2ecbadcd36 up to, but not including, 9a18629f2525781f0f3dda7be72b204e4cf77d08; f2fc6a54585a1be6669613a31fbaba2ecbadcd36 up to, but not including, 63d45077b97bb0e0fe0c75931acbbca7a47af141; f2fc6a54585a1be6669613a31fbaba2ecbadcd36 up to, but not including, ba8bda9a0896746053aa97ac6c3e08168729172c; and 1 more ranges | be0e63f3b97bbaf453c542e8a15ba2a536e2ac01, c1ec36cb3768574b916f20d2d7415fd14fa1bf12, 8a4790850e710fd6771e4d2112168ed1dd6c0e54, fedd2e1630cac920844997227ccbe7b26a76375a, f04733c4dc40c43899c3d1c97afbae5831a3770f, 9a18629f2525781f0f3dda7be72b204e4cf77d08 |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Linux | Linux Kernel | 2.6.26 up to, but not including, 5.10.253; 5.11 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.168; 6.2 up to, but not including, 6.6.131; 6.7 up to, but not including, 6.12.80; 6.13 up to, but not including, 6.18.21; 6.19 up to, but not including, 6.19.11; 7.0 | 5.10.253, 5.15.203, 6.1.168, 6.6.131, 6.12.80, 6.18.21 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.
Official 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
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/63d45077b97bb0e0fe0c75931acbbca7a47af141
- git.kernel.org/stable/c/8a4790850e710fd6771e4d2112168ed1dd6c0e54
- git.kernel.org/stable/c/9a18629f2525781f0f3dda7be72b204e4cf77d08
- git.kernel.org/stable/c/ba8bda9a0896746053aa97ac6c3e08168729172c
- git.kernel.org/stable/c/be0e63f3b97bbaf453c542e8a15ba2a536e2ac01
- git.kernel.org/stable/c/c1ec36cb3768574b916f20d2d7415fd14fa1bf12
- git.kernel.org/stable/c/f04733c4dc40c43899c3d1c97afbae5831a3770f
- git.kernel.org/stable/c/fedd2e1630cac920844997227ccbe7b26a76375a
Other references
Recent Use After Free vulnerabilities
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