Linux Kernel xfrm net/ipv6/xfrm6_policy.c xfrm6_fill_dst use after free

Summaryinfo

A vulnerability was found in Linux Kernel. It has been classified as very critical. Impacted is the function xfrm6_fill_dst of the file net/ipv6/xfrm6_policy.c of the component xfrm. This manipulation causes use after free. This vulnerability is registered as CVE-2026-98364. Remote exploitation of the attack is possible. No exploit is available. It is suggested to install a patch to address this issue.

Detailsinfo

A vulnerability has been found in Linux Kernel (unknown version) and classified as very critical. Affected by this vulnerability is the function xfrm6_fill_dst of the file net/ipv6/xfrm6_policy.c of the component xfrm. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: xfrm: hold net_device reference under RCU in bundle creation xfrm_bundle_create() and xfrm_create_dummy_bundle() read dst->dev into a local pointer without taking a device reference, then pass it to xfrm_fill_dst(). A concurrent RTM_DELLINK replaces dst->dev via dst_dev_put() and frees the old net_device, causing a use-after-free when xfrm6_fill_dst() later dereferences the stale dev pointer. BUG: KASAN: slab-use-after-free in xfrm6_fill_dst+0x82c/0x860 (net/ipv6/xfrm6_policy.c:86 netdev_hold()) Read of size 8 at addr ffff8880142fe588 by task exploit/153 Call Trace: xfrm6_fill_dst+0x82c/0x860 xfrm_resolve_and_create_bundle+0x21d4/0x2bd0 xfrm_lookup_with_ifid+0x485/0x1640 ip6_dst_lookup_flow+0x19b/0x1e0 udpv6_sendmsg+0x1443/0x2dd0 Fix this by reading dst->dev via dst_dev_rcu() and keeping the RCU read-side critical section active until xfrm_fill_dst() has taken the required device references.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-98364 since 09/25/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 10/06/2026).

Applying the patch 8d85d6bc9c46dc41cb2be0eac53f8ab068c3a807 is able to eliminate this problem.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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