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ipv4: fib: Don't dump dying fib_info in fib_leaf_notify().

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: ipv4: fib: Don't dump dying fib_info in fib_leaf_notify(). syzbot reported use-after-free in nsim_fib4_prepare_event(). [0] The problem is that the following functions call fib_info_hold() / refcount_inc() while dumping fib_info under RCU, which is unsafe. * mlxsw_sp_router_fib4_event() * rocker_router_fib_event() * nsim_fib4_prepare_event() refcount_inc_not_zero() must be used, but it would be too late there. Let's guarantee the lifetime of fib_info in fib_leaf_notify(). Note that IPv6 does not need the corresponding change since fib6_table_dump() holds fib6_table.tb6_lock. [0]: refcount_t: addition on 0; use-after-free. WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25, CPU#0: kworker/u8:15/3420 Modules linked in: CPU: 0 UID: 0 PID: 3420 Comm: kworker/u8:15 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Workqueue: netns cleanup_net RIP: 0010:refcount_warn_saturate+0x9f/0x110 lib/refcount.c:25 Code: eb 66 85 db 74 3e 83 fb 01 75 4c e8 1b f1 22 fd 48 8d 3d 84 cb f1 0a 67 48 0f b9 3a eb 4a e8 08 f1 22 fd 48 8d 3d 81 cb f1 0a <67> 48 0f b9 3a eb 37 e8 f5 f0 22 fd 48 8d 3d 7e cb f1 0a 67 48 0f RSP: 0018:ffffc9000f2c7270 EFLAGS: 00010293 RAX: ffffffff84a18858 RBX: 0000000000000002 RCX: ffff888032ff9ec0 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8f9353e0 RBP: 0000000000000000 R08: f

Announced Source revision 1
Original source ↗

CVE-2026-74289

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-2026-74289

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": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
        "lessThan": "8bdb20b8a581495062b5879f4e9d435da648b3b0",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
        "lessThan": "7907a395701b339c2d68f37456d395e953c74795",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
        "lessThan": "7980a13add57f97c5da1dc961d0145a6ad2a7f98",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
        "lessThan": "bea03e887db5a8a79234531faf14cf2c4d8816c3",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
        "lessThan": "676482da8d938ea72c26da0fc86af2d2ec238ab2",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c3852ef7f2f8f75a9f85a864bec1f6f5a3068eea",
        "lessThan": "06b693d2eb6651a63ad85bad8673de3b7d4edd6d",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "include/net/ip_fib.h",
      "net/ipv4/fib_trie.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.10"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.10",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.1.189",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.158",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.111",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.53",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.5",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "include/net/ip_fib.h",
      "net/ipv4/fib_trie.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-74289

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#33083 · Revision 1
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Publisher date
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