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ipv6: rpl: fix NULL dereference of idev in ipv6_rpl_srh_rcv()

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: ipv6: rpl: fix NULL dereference of idev in ipv6_rpl_srh_rcv() ipv6_rpl_srh_rcv() dereferences idev from __in6_dev_get() without a NULL check when reading idev->cnf.rpl_seg_enabled. When the device's MTU drops below IPV6_MIN_MTU, addrconf_ifdown() clears dev->ip6_ptr through RCU_INIT_POINTER(). A packet that passed the idev check in ip6_rcv_core() can then reach ipv6_rpl_srh_rcv() with dev->ip6_ptr already NULL. Reproduced by flooding the receiving interface with ping6 traffic while flapping its MTU between 1500 and 1200: BUG: KASAN: null-ptr-deref in ipv6_rpl_srh_rcv+0xb3/0x1070 Read of size 4 at addr 00000000000006b4 by task ping6/394 CPU: 2 UID: 0 PID: 394 Comm: ping6 Not tainted 7.2.0-rc7-micro-vm-dev-00095-g24ef02f934ee #240 PREEMPT(full) Call Trace: kasan_report+0xc6/0x100 ipv6_rpl_srh_rcv+0xb3/0x1070 ip6_protocol_deliver_rcu+0x759/0x9a0 ip6_input_finish+0xa8/0x1b0 ip6_input+0xe1/0x490 ipv6_rcv+0x33d/0x460 __netif_receive_skb_one_core+0xd6/0x130 process_backlog+0x2cc/0xa00 __napi_poll.constprop.0+0x56/0x270 net_rx_action+0x327/0x730 handle_softirqs+0x11e/0x630 do_softirq+0xb3/0xf0 Both ipv6_rpl_srh_rcv() and ipv6_srh_rcv() are called only from ipv6_rthdr_rcv(), which already has an idev lookup. Fix the NULL dereference on the RPL path by checking idev in ipv6_rthdr_rcv(), before it calls either function. The callees take idev as an argument and no longer call __in6_dev_get(), so the packet is now dropped

Announced Source revision 1
Original source ↗

CVE-2026-89561

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-89561

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
        "lessThan": "62b63a505c10e8db76017ef73c0b243e0dc5d288",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
        "lessThan": "e7123e10c86eb88eaa90537dd1f232706de2d308",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
        "lessThan": "63f50e9f90d0287ad66a0955ebfc2d3a9c044a1c",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
        "lessThan": "eab3a917cdcb182542a3aac6a0d2d30659ca9821",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
        "lessThan": "f826df95332c07380206dbd54178b6eefb311aba",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/ipv6/exthdrs.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.7"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.7",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.111",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.50",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.4",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/ipv6/exthdrs.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-89561

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#46679 · Revision 1
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Publisher date
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