CVE-2026-64436 (GCVE-0-2026-64436)
Vulnerability from cvelistv5
Published
2026-07-25 08:51
Modified
2026-08-17 04:55
Severity ?
7.1 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: net: af_key: initialize alg_key_len for IPComp states pfkey_msg2xfrm_state() handles the IPComp (SADB_X_SATYPE_IPCOMP) case by allocating x->calg and copying only the algorithm name: x->calg = kmalloc_obj(*x->calg); if (!x->calg) { err = -ENOMEM; goto out; } strcpy(x->calg->alg_name, a->name); x->props.calgo = sa->sadb_sa_encrypt; Unlike the authentication (x->aalg) and encryption (x->ealg) branches of the same function, the compression branch never initializes calg->alg_key_len. IPComp carries no key and the allocation only reserves sizeof(struct xfrm_algo) (i.e. no room for a key), so the field is left containing uninitialized slab data. calg->alg_key_len is later used as a length by xfrm_algo_clone() when an IPComp state is cloned during XFRM_MSG_MIGRATE: xfrm_state_migrate() xfrm_state_clone_and_setup() x->calg = xfrm_algo_clone(orig->calg); kmemdup(orig, xfrm_alg_len(orig)); where xfrm_alg_len() returns sizeof(*alg) + (alg_key_len + 7) / 8. With a non-zero garbage alg_key_len, kmemdup() reads past the end of the 68-byte calg object. Adding an IPComp SA via PF_KEY and then migrating it triggers (net-next, KASAN, init_on_alloc=0): BUG: KASAN: slab-out-of-bounds in kmemdup_noprof+0x44/0x60 Read of size 4164 at addr ff11000025a74980 by task diag2/9287 CPU: 3 UID: 0 PID: 9287 Comm: diag2 7.1.0-rc6-g903db046d557 #1 Call Trace: <TASK> dump_stack_lvl+0x10e/0x1f0 print_report+0xf7/0x600 kasan_report+0xe4/0x120 kasan_check_range+0x105/0x1b0 __asan_memcpy+0x23/0x60 kmemdup_noprof+0x44/0x60 xfrm_state_migrate+0x70a/0x1da0 xfrm_migrate+0x753/0x18a0 xfrm_do_migrate+0xb47/0xf10 xfrm_user_rcv_msg+0x411/0xb50 netlink_rcv_skb+0x158/0x420 xfrm_netlink_rcv+0x71/0x90 netlink_unicast+0x584/0x850 netlink_sendmsg+0x8b0/0xdc0 ____sys_sendmsg+0x9f7/0xb90 ___sys_sendmsg+0x134/0x1d0 __sys_sendmsg+0x16d/0x220 do_syscall_64+0x116/0x7d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK> Allocated by task 9287: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 pfkey_add+0x2652/0x2ea0 pfkey_process+0x6d0/0x830 pfkey_sendmsg+0x42c/0x850 __sys_sendto+0x461/0x4b0 __x64_sys_sendto+0xe0/0x1c0 do_syscall_64+0x116/0x7d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ff11000025a74980 which belongs to the cache kmalloc-96 of size 96 The buggy address is located 0 bytes inside of allocated 68-byte region [ff11000025a74980, ff11000025a749c4) Depending on the uninitialized value the same field can instead request an oversized kmemdup() allocation and make the migration clone fail. The XFRM netlink path is not affected: verify_one_alg() rejects an XFRMA_ALG_COMP attribute shorter than xfrm_alg_len(), so a calg added via XFRM_MSG_NEWSA is always self-consistent. Initialize calg->alg_key_len to 0, matching the aalg/ealg branches.
References
Impacted products
Vendor Product Version
Linux Linux Version: 80c9abaabf4283f7cf4a0b3597cd302506635b7f
Version: 80c9abaabf4283f7cf4a0b3597cd302506635b7f
Version: 80c9abaabf4283f7cf4a0b3597cd302506635b7f
Version: 80c9abaabf4283f7cf4a0b3597cd302506635b7f
Version: 80c9abaabf4283f7cf4a0b3597cd302506635b7f
Version: 80c9abaabf4283f7cf4a0b3597cd302506635b7f
Version: 80c9abaabf4283f7cf4a0b3597cd302506635b7f
Version: 80c9abaabf4283f7cf4a0b3597cd302506635b7f
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{
  "containers": {
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/key/af_key.c"
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          "vendor": "Linux",
          "versions": [
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            },
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              "version": "0",
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              "status": "unaffected",
              "version": "5.10.261",
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            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.212",
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            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.178",
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            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.145",
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            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.96",
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            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
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              "status": "unaffected",
              "version": "7.1.4",
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            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
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                  "versionEndExcluding": "7.2",
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                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: af_key: initialize alg_key_len for IPComp states\n\npfkey_msg2xfrm_state() handles the IPComp (SADB_X_SATYPE_IPCOMP) case by\nallocating x-\u003ecalg and copying only the algorithm name:\n\n\tx-\u003ecalg = kmalloc_obj(*x-\u003ecalg);\n\tif (!x-\u003ecalg) {\n\t\terr = -ENOMEM;\n\t\tgoto out;\n\t}\n\tstrcpy(x-\u003ecalg-\u003ealg_name, a-\u003ename);\n\tx-\u003eprops.calgo = sa-\u003esadb_sa_encrypt;\n\nUnlike the authentication (x-\u003eaalg) and encryption (x-\u003eealg) branches of\nthe same function, the compression branch never initializes\ncalg-\u003ealg_key_len.  IPComp carries no key and the allocation only\nreserves sizeof(struct xfrm_algo) (i.e. no room for a key), so the field\nis left containing uninitialized slab data.\n\ncalg-\u003ealg_key_len is later used as a length by xfrm_algo_clone() when an\nIPComp state is cloned during XFRM_MSG_MIGRATE:\n\n\txfrm_state_migrate()\n\t  xfrm_state_clone_and_setup()\n\t    x-\u003ecalg = xfrm_algo_clone(orig-\u003ecalg);\n\t      kmemdup(orig, xfrm_alg_len(orig));\n\nwhere xfrm_alg_len() returns sizeof(*alg) + (alg_key_len + 7) / 8.  With\na non-zero garbage alg_key_len, kmemdup() reads past the end of the\n68-byte calg object.  Adding an IPComp SA via PF_KEY and then migrating\nit triggers (net-next, KASAN, init_on_alloc=0):\n\n  BUG: KASAN: slab-out-of-bounds in kmemdup_noprof+0x44/0x60\n  Read of size 4164 at addr ff11000025a74980 by task diag2/9287\n  CPU: 3 UID: 0 PID: 9287 Comm: diag2 7.1.0-rc6-g903db046d557 #1\n  Call Trace:\n   \u003cTASK\u003e\n   dump_stack_lvl+0x10e/0x1f0\n   print_report+0xf7/0x600\n   kasan_report+0xe4/0x120\n   kasan_check_range+0x105/0x1b0\n   __asan_memcpy+0x23/0x60\n   kmemdup_noprof+0x44/0x60\n   xfrm_state_migrate+0x70a/0x1da0\n   xfrm_migrate+0x753/0x18a0\n   xfrm_do_migrate+0xb47/0xf10\n   xfrm_user_rcv_msg+0x411/0xb50\n   netlink_rcv_skb+0x158/0x420\n   xfrm_netlink_rcv+0x71/0x90\n   netlink_unicast+0x584/0x850\n   netlink_sendmsg+0x8b0/0xdc0\n   ____sys_sendmsg+0x9f7/0xb90\n   ___sys_sendmsg+0x134/0x1d0\n   __sys_sendmsg+0x16d/0x220\n   do_syscall_64+0x116/0x7d0\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n   \u003c/TASK\u003e\n\n  Allocated by task 9287:\n   kasan_save_stack+0x33/0x60\n   kasan_save_track+0x14/0x30\n   __kasan_kmalloc+0xaa/0xb0\n   pfkey_add+0x2652/0x2ea0\n   pfkey_process+0x6d0/0x830\n   pfkey_sendmsg+0x42c/0x850\n   __sys_sendto+0x461/0x4b0\n   __x64_sys_sendto+0xe0/0x1c0\n   do_syscall_64+0x116/0x7d0\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\n  The buggy address belongs to the object at ff11000025a74980\n   which belongs to the cache kmalloc-96 of size 96\n  The buggy address is located 0 bytes inside of\n   allocated 68-byte region [ff11000025a74980, ff11000025a749c4)\n\nDepending on the uninitialized value the same field can instead request\nan oversized kmemdup() allocation and make the migration clone fail.\n\nThe XFRM netlink path is not affected: verify_one_alg() rejects an\nXFRMA_ALG_COMP attribute shorter than xfrm_alg_len(), so a calg added via\nXFRM_MSG_NEWSA is always self-consistent.\n\nInitialize calg-\u003ealg_key_len to 0, matching the aalg/ealg branches."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - Exploitation requires local PF_KEY and XFRM netlink messages; received IPComp network packets cannot create or migrate the vulnerable state.\nAC:L - The attacker can deterministically prime the same kmalloc-96 cache and control the stale length before triggering migration. No race or victim-controlled condition is required.\nPR:L - Both paths require CAP_NET_ADMIN relative to the network namespace\u0027s owning user namespace. An unprivileged user can obtain this capability in a newly created user and network namespace.\nUI:N - No victim action is required after the attacker gains local execution and submits the crafted state and migration messages.\nS:U - The vulnerability affects the host kernel within its existing security authority and does not cross a VM, IOMMU, or equivalent scope boundary.\nC:H - The controlled length causes a potentially large out-of-bounds read across adjacent kernel heap objects, which can capture sensitive kernel memory and is not tightly bounded.\nI:N - kmemdup allocates a destination matching the computed length, and the vulnerable operation only over-reads the source. No out-of-bounds write or control-flow modification path was identified.\nA:H - The over-read can trigger a kernel fault or panic under memory-safety enforcement. Controlled oversized clone allocations can also be repeated across states to exhaust kernel memory."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:55:37.549Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/58e82fc3dedb57b1432292504415b224fd2d6acb"
        },
        {
          "url": "https://git.kernel.org/stable/c/01b9115b55018123ef2449ac4951f89147a8428e"
        },
        {
          "url": "https://git.kernel.org/stable/c/3f63d1752d90c0e28be931a48ab5d89bc97d637d"
        },
        {
          "url": "https://git.kernel.org/stable/c/273c06b81d2e902b21acc801ae18c8276c8a9b69"
        },
        {
          "url": "https://git.kernel.org/stable/c/6de2a650917bedaaefd65b17cede83c5e2c1dedd"
        },
        {
          "url": "https://git.kernel.org/stable/c/e8417353cbd078d10531ba3928e609c84ab09e6b"
        },
        {
          "url": "https://git.kernel.org/stable/c/cea34abc94b0a81e3a8b5cfb41cf45af37c2c67e"
        },
        {
          "url": "https://git.kernel.org/stable/c/d129c3177d7b1138fd5066fcc63a698b3ba415b0"
        }
      ],
      "title": "net: af_key: initialize alg_key_len for IPComp states",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64436",
    "datePublished": "2026-07-25T08:51:10.370Z",
    "dateReserved": "2026-07-19T15:36:31.787Z",
    "dateUpdated": "2026-08-17T04:55:37.549Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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