CVE-2026-98364 (GCVE-0-2026-98364)

Vulnerability from cvelistv5 – Published: 2026-10-06 08:46 – Updated: 2026-10-07 06:50
VLAI
Title
xfrm: hold net_device reference under RCU in bundle creation
Summary
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.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 25ee3286dcbc830a833354bb1d15567956844813 , < 8d85d6bc9c46dc41cb2be0eac53f8ab068c3a807 (git)
Affected: 25ee3286dcbc830a833354bb1d15567956844813 , < 9fa903b24b1f46b4ff5443bcd4aca23e5c57f9c1 (git)
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Linux Linux Affected: 2.6.25
Unaffected: 0 , < 2.6.25 (semver)
Unaffected: 7.2.8 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc4 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/xfrm/xfrm_policy.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              "operator": "OR"
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        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: hold net_device reference under RCU in bundle creation\n\nxfrm_bundle_create() and xfrm_create_dummy_bundle() read dst-\u003edev into\na local pointer without taking a device reference, then pass it to\nxfrm_fill_dst(). A concurrent RTM_DELLINK replaces dst-\u003edev via\ndst_dev_put() and frees the old net_device, causing a use-after-free\nwhen xfrm6_fill_dst() later dereferences the stale dev pointer.\n\n  BUG: KASAN: slab-use-after-free in xfrm6_fill_dst+0x82c/0x860\n  (net/ipv6/xfrm6_policy.c:86 netdev_hold())\n  Read of size 8 at addr ffff8880142fe588 by task exploit/153\n  Call Trace:\n   xfrm6_fill_dst+0x82c/0x860\n   xfrm_resolve_and_create_bundle+0x21d4/0x2bd0\n   xfrm_lookup_with_ifid+0x485/0x1640\n   ip6_dst_lookup_flow+0x19b/0x1e0\n   udpv6_sendmsg+0x1443/0x2dd0\n\nFix this by reading dst-\u003edev via dst_dev_rcu() and keeping the RCU\nread-side critical section active until xfrm_fill_dst() has taken the\nrequired device references."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "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"
          },
          "scenarios": [
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              "lang": "en",
              "value": "AV:L - Both sides of the race are local syscalls: sendmsg() (udpv6_sendmsg-\u003eip6_dst_lookup_flow-\u003exfrm_lookup_with_ifid-\u003exfrm_bundle_create) and an RTM_DELLINK rtnetlink request that frees the net_device. A remote peer cannot delete the link, so the network cannot cause the freed state.\nAC:L - The attacker controls both sides of the race: they repeatedly send through an xfrm-policy-matched route while deleting the link in a loop. The window between reading dst-\u003edev and netdev_hold() in xfrm_fill_dst() is short, but the attacker can retry as often as needed.\nPR:L - xfrm_user_rcv_msg only checks netlink_net_capable(CAP_NET_ADMIN), and RTM_DELLINK is also checked per namespace. An unprivileged user with unshare -Urn can create a device, install the XFRM policy and state, and delete the device inside their own network namespace.\nUI:N - No victim action is needed: the attacker sets up the namespace, the xfrm configuration, the sending socket and the link deletion entirely on their own.\nS:U - The use-after-free is inside the kernel\u0027s own networking code and the impact stays within the kernel\u0027s security authority; no VM or IOMMU boundary is crossed.\nC:H - xfrm6_fill_dst() reads dev-\u003eip6_ptr from the freed net_device through in6_dev_get() and stores the stale dev in a new dst. A reclaimed object controls those values, which can be used to disclose kernel memory.\nI:H - netdev_hold() increments a refcount inside the freed net_device, and in6_dev_get() increments a refcount on a pointer taken from the reclaimed object. Both are writes into attacker-reclaimable slab memory, usable to corrupt kernel data and hijack control flow.\nA:H - KASAN reports a slab-use-after-free in xfrm6_fill_dst(). On production kernels the stale dev stays attached to the new xfrm dst and is dereferenced later, which leads to an oops or panic."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-07T06:50:17.322Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/8d85d6bc9c46dc41cb2be0eac53f8ab068c3a807"
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          "url": "https://git.kernel.org/stable/c/9fa903b24b1f46b4ff5443bcd4aca23e5c57f9c1"
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      "title": "xfrm: hold net_device reference under RCU in bundle creation",
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        "engine": "bippy-1.2.0"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98364",
    "datePublished": "2026-10-06T08:46:50.051Z",
    "dateReserved": "2026-09-25T10:25:14.344Z",
    "dateUpdated": "2026-10-07T06:50:17.322Z",
    "state": "PUBLISHED"
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        "descriptions": [
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            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: hold net_device reference under RCU in bundle creation\n\nxfrm_bundle_create() and xfrm_create_dummy_bundle() read dst-\u003edev into\na local pointer without taking a device reference, then pass it to\nxfrm_fill_dst(). A concurrent RTM_DELLINK replaces dst-\u003edev via\ndst_dev_put() and frees the old net_device, causing a use-after-free\nwhen xfrm6_fill_dst() later dereferences the stale dev pointer.\n\n  BUG: KASAN: slab-use-after-free in xfrm6_fill_dst+0x82c/0x860\n  (net/ipv6/xfrm6_policy.c:86 netdev_hold())\n  Read of size 8 at addr ffff8880142fe588 by task exploit/153\n  Call Trace:\n   xfrm6_fill_dst+0x82c/0x860\n   xfrm_resolve_and_create_bundle+0x21d4/0x2bd0\n   xfrm_lookup_with_ifid+0x485/0x1640\n   ip6_dst_lookup_flow+0x19b/0x1e0\n   udpv6_sendmsg+0x1443/0x2dd0\n\nFix this by reading dst-\u003edev via dst_dev_rcu() and keeping the RCU\nread-side critical section active until xfrm_fill_dst() has taken the\nrequired device references."
          }
        ],
        "id": "CVE-2026-98364",
        "lastModified": "2026-10-07T07:17:10.717",
        "metrics": {
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                "attackVector": "LOCAL",
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                "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",
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              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "published": "2026-10-06T09:18:30.547",
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/8d85d6bc9c46dc41cb2be0eac53f8ab068c3a807"
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
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}



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