CVE-2026-43139 (GCVE-0-2026-43139)
Vulnerability from cvelistv5
Published
2026-05-06 11:27
Modified
2026-08-05 12:26
Severity ?
8.6 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: xfrm6: fix uninitialized saddr in xfrm6_get_saddr() xfrm6_get_saddr() does not check the return value of ipv6_dev_get_saddr(). When ipv6_dev_get_saddr() fails to find a suitable source address (returns -EADDRNOTAVAIL), saddr->in6 is left uninitialized, but xfrm6_get_saddr() still returns 0 (success). This causes the caller xfrm_tmpl_resolve_one() to use the uninitialized address in xfrm_state_find(), triggering KMSAN warning: ===================================================== BUG: KMSAN: uninit-value in xfrm_state_find+0x2424/0xa940 xfrm_state_find+0x2424/0xa940 xfrm_resolve_and_create_bundle+0x906/0x5a20 xfrm_lookup_with_ifid+0xcc0/0x3770 xfrm_lookup_route+0x63/0x2b0 ip_route_output_flow+0x1ce/0x270 udp_sendmsg+0x2ce1/0x3400 inet_sendmsg+0x1ef/0x2a0 __sock_sendmsg+0x278/0x3d0 __sys_sendto+0x593/0x720 __x64_sys_sendto+0x130/0x200 x64_sys_call+0x332b/0x3e70 do_syscall_64+0xd3/0xf80 entry_SYSCALL_64_after_hwframe+0x77/0x7f Local variable tmp.i.i created at: xfrm_resolve_and_create_bundle+0x3e3/0x5a20 xfrm_lookup_with_ifid+0xcc0/0x3770 ===================================================== Fix by checking the return value of ipv6_dev_get_saddr() and propagating the error.
References
Impacted products
Vendor Product Version
Linux Linux Version: a1e59abf824969554b90facd44a4ab16e265afa4
Version: a1e59abf824969554b90facd44a4ab16e265afa4
Version: a1e59abf824969554b90facd44a4ab16e265afa4
Version: a1e59abf824969554b90facd44a4ab16e265afa4
Version: a1e59abf824969554b90facd44a4ab16e265afa4
Version: a1e59abf824969554b90facd44a4ab16e265afa4
Version: a1e59abf824969554b90facd44a4ab16e265afa4
Version: a1e59abf824969554b90facd44a4ab16e265afa4
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{
  "containers": {
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/xfrm6_policy.c"
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              "version": "0",
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      "cpeApplicability": [
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              ],
              "negate": false,
              "operator": "OR"
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          ]
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm6: fix uninitialized saddr in xfrm6_get_saddr()\n\nxfrm6_get_saddr() does not check the return value of\nipv6_dev_get_saddr(). When ipv6_dev_get_saddr() fails to find a suitable\nsource address (returns -EADDRNOTAVAIL), saddr-\u003ein6 is left\nuninitialized, but xfrm6_get_saddr() still returns 0 (success).\n\nThis causes the caller xfrm_tmpl_resolve_one() to use the uninitialized\naddress in xfrm_state_find(), triggering KMSAN warning:\n\n=====================================================\nBUG: KMSAN: uninit-value in xfrm_state_find+0x2424/0xa940\n xfrm_state_find+0x2424/0xa940\n xfrm_resolve_and_create_bundle+0x906/0x5a20\n xfrm_lookup_with_ifid+0xcc0/0x3770\n xfrm_lookup_route+0x63/0x2b0\n ip_route_output_flow+0x1ce/0x270\n udp_sendmsg+0x2ce1/0x3400\n inet_sendmsg+0x1ef/0x2a0\n __sock_sendmsg+0x278/0x3d0\n __sys_sendto+0x593/0x720\n __x64_sys_sendto+0x130/0x200\n x64_sys_call+0x332b/0x3e70\n do_syscall_64+0xd3/0xf80\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nLocal variable tmp.i.i created at:\n xfrm_resolve_and_create_bundle+0x3e3/0x5a20\n xfrm_lookup_with_ifid+0xcc0/0x3770\n=====================================================\n\nFix by checking the return value of ipv6_dev_get_saddr() and propagating\nthe error."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.6,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - A network-triggered path exists on an IPv6/IPsec endpoint: received IPv6 traffic that causes kernel-generated output, such as ICMPv6/NDISC replies or service responses, enters xfrm_lookup_route() and reaches xfrm_tmpl_resolve_one()-\u003exfrm6_get_saddr(). The same code is locally reachable with sendmsg(), but a reasonably configured XFRM/IPsec host can be triggered by network traffic.\nAC:L - No race, heap grooming, or timing condition is required; once the affected outbound XFRM template has a wildcard IPv6 tunnel source and source address selection fails, the unchecked error path is deterministic. Matching output traffic can be triggered repeatedly.\nPR:N - The network trigger does not require the attacker to authenticate or hold local privileges. Creating the XFRM policy requires CAP_NET_ADMIN, including via a user/net namespace for local testing, but in the network scenario that policy is preexisting victim configuration.\nUI:N - No victim user action is required after the vulnerable XFRM/IPsec configuration is present. Packets or local sends directly drive the kernel output path.\nS:U - The bug affects kernel XFRM/IPv6 processing within the same host security authority. It does not cross a VM, IOMMU, or separate security scope boundary.\nC:L - The uninitialized value is a bounded 16-byte IPv6 source address from kernel stack, used in hashes/comparisons and potentially copied into XFRM acquire state/messages. This is limited kernel memory disclosure, not an arbitrary read primitive.\nI:L - The uninitialized source address can influence XFRM state lookup/acquire behavior and create or notify state using an unintended local tunnel endpoint. This is limited integrity impact to IPsec/XFRM state handling, not arbitrary modification.\nA:H - Syzbot reported a kernel BUG/KMSAN finding in xfrm_state_find(), and the bad value is consumed in core XFRM state lookup/acquire paths that can be triggered repeatedly. Kernel warning/oops/panic conditions are high availability impact."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:26:11.398Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/4f28141786e1fe884ce42a5197ba9beed540f0ea"
        },
        {
          "url": "https://git.kernel.org/stable/c/6535867673bf301d52aa00593a4d1d18cc3922fa"
        },
        {
          "url": "https://git.kernel.org/stable/c/eb2ee15290af14c60b45cf2b73f5687d1d077d9b"
        },
        {
          "url": "https://git.kernel.org/stable/c/719918fc88df6da023dfff370cd965151a5afd7f"
        },
        {
          "url": "https://git.kernel.org/stable/c/dc0abce055134cb83b0d981d31ceb20dda419787"
        },
        {
          "url": "https://git.kernel.org/stable/c/c7221e7bd8fc2ef38a0b27be580d9d202281306b"
        },
        {
          "url": "https://git.kernel.org/stable/c/3dcd1664ac15eee6a690daec7c4ffc59190406f7"
        },
        {
          "url": "https://git.kernel.org/stable/c/1799d8abeabc68ec05679292aaf6cba93b343c05"
        }
      ],
      "title": "xfrm6: fix uninitialized saddr in xfrm6_get_saddr()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43139",
    "datePublished": "2026-05-06T11:27:24.898Z",
    "dateReserved": "2026-05-01T14:12:55.988Z",
    "dateUpdated": "2026-08-05T12:26:11.398Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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