Vulnerability-Lookup

GHSA-RGJ2-XQ4C-HRVM

Vulnerability from github – Published: 2026-01-21 15:31 – Updated: 2026-01-21 15:31

Details

In the Linux kernel, the following vulnerability has been resolved:

net: sock: fix hardened usercopy panic in sock_recv_errqueue

skbuff_fclone_cache was created without defining a usercopy region, [1] unlike skbuff_head_cache which properly whitelists the cb[] field. [2] This causes a usercopy BUG() when CONFIG_HARDENED_USERCOPY is enabled and the kernel attempts to copy sk_buff.cb data to userspace via sock_recv_errqueue() -> put_cmsg().

The crash occurs when: 1. TCP allocates an skb using alloc_skb_fclone() (from skbuff_fclone_cache) [1] 2. The skb is cloned via skb_clone() using the pre-allocated fclone [3] 3. The cloned skb is queued to sk_error_queue for timestamp reporting 4. Userspace reads the error queue via recvmsg(MSG_ERRQUEUE) 5. sock_recv_errqueue() calls put_cmsg() to copy serr->ee from skb->cb [4] 6. __check_heap_object() fails because skbuff_fclone_cache has no usercopy whitelist [5]

When cloned skbs allocated from skbuff_fclone_cache are used in the socket error queue, accessing the sock_exterr_skb structure in skb->cb via put_cmsg() triggers a usercopy hardening violation:

[ 5.379589] usercopy: Kernel memory exposure attempt detected from SLUB object 'skbuff_fclone_cache' (offset 296, size 16)! [ 5.382796] kernel BUG at mm/usercopy.c:102! [ 5.383923] Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI [ 5.384903] CPU: 1 UID: 0 PID: 138 Comm: poc_put_cmsg Not tainted 6.12.57 #7 [ 5.384903] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 5.384903] RIP: 0010:usercopy_abort+0x6c/0x80 [ 5.384903] Code: 1a 86 51 48 c7 c2 40 15 1a 86 41 52 48 c7 c7 c0 15 1a 86 48 0f 45 d6 48 c7 c6 80 15 1a 86 48 89 c1 49 0f 45 f3 e8 84 27 88 ff <0f> 0b 490 [ 5.384903] RSP: 0018:ffffc900006f77a8 EFLAGS: 00010246 [ 5.384903] RAX: 000000000000006f RBX: ffff88800f0ad2a8 RCX: 1ffffffff0f72e74 [ 5.384903] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff87b973a0 [ 5.384903] RBP: 0000000000000010 R08: 0000000000000000 R09: fffffbfff0f72e74 [ 5.384903] R10: 0000000000000003 R11: 79706f6372657375 R12: 0000000000000001 [ 5.384903] R13: ffff88800f0ad2b8 R14: ffffea00003c2b40 R15: ffffea00003c2b00 [ 5.384903] FS: 0000000011bc4380(0000) GS:ffff8880bf100000(0000) knlGS:0000000000000000 [ 5.384903] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 5.384903] CR2: 000056aa3b8e5fe4 CR3: 000000000ea26004 CR4: 0000000000770ef0 [ 5.384903] PKRU: 55555554 [ 5.384903] Call Trace: [ 5.384903] [ 5.384903] __check_heap_object+0x9a/0xd0 [ 5.384903] __check_object_size+0x46c/0x690 [ 5.384903] put_cmsg+0x129/0x5e0 [ 5.384903] sock_recv_errqueue+0x22f/0x380 [ 5.384903] tls_sw_recvmsg+0x7ed/0x1960 [ 5.384903] ? srso_alias_return_thunk+0x5/0xfbef5 [ 5.384903] ? schedule+0x6d/0x270 [ 5.384903] ? srso_alias_return_thunk+0x5/0xfbef5 [ 5.384903] ? mutex_unlock+0x81/0xd0 [ 5.384903] ? __pfx_mutex_unlock+0x10/0x10 [ 5.384903] ? __pfx_tls_sw_recvmsg+0x10/0x10 [ 5.384903] ? _raw_spin_lock_irqsave+0x8f/0xf0 [ 5.384903] ? _raw_read_unlock_irqrestore+0x20/0x40 [ 5.384903] ? srso_alias_return_thunk+0x5/0xfbef5

The crash offset 296 corresponds to skb2->cb within skbuff_fclones: - sizeof(struct sk_buff) = 232 - offsetof(struct sk_buff, cb) = 40 - offset of skb2.cb in fclones = 232 + 40 = 272 - crash offset 296 = 272 + 24 (inside sock_exterr_skb.ee)

This patch uses a local stack variable as a bounce buffer to avoid the hardened usercopy check failure.

[1] https://elixir.bootlin.com/linux/v6.12.62/source/net/ipv4/tcp.c#L885 [2] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5104 [3] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5566 [4] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5491 [5] https://elixir.bootlin.com/linux/v6.12.62/source/mm/slub.c#L5719

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{
  "affected": [],
  "aliases": [
    "CVE-2026-22977"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-01-21T14:16:06Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: sock: fix hardened usercopy panic in sock_recv_errqueue\n\nskbuff_fclone_cache was created without defining a usercopy region,\n[1] unlike skbuff_head_cache which properly whitelists the cb[] field.\n[2] This causes a usercopy BUG() when CONFIG_HARDENED_USERCOPY is\nenabled and the kernel attempts to copy sk_buff.cb data to userspace\nvia sock_recv_errqueue() -\u003e put_cmsg().\n\nThe crash occurs when: 1. TCP allocates an skb using alloc_skb_fclone()\n   (from skbuff_fclone_cache) [1]\n2. The skb is cloned via skb_clone() using the pre-allocated fclone\n[3] 3. The cloned skb is queued to sk_error_queue for timestamp\nreporting 4. Userspace reads the error queue via recvmsg(MSG_ERRQUEUE)\n5. sock_recv_errqueue() calls put_cmsg() to copy serr-\u003eee from skb-\u003ecb\n[4] 6. __check_heap_object() fails because skbuff_fclone_cache has no\n   usercopy whitelist [5]\n\nWhen cloned skbs allocated from skbuff_fclone_cache are used in the\nsocket error queue, accessing the sock_exterr_skb structure in skb-\u003ecb\nvia put_cmsg() triggers a usercopy hardening violation:\n\n[    5.379589] usercopy: Kernel memory exposure attempt detected from SLUB object \u0027skbuff_fclone_cache\u0027 (offset 296, size 16)!\n[    5.382796] kernel BUG at mm/usercopy.c:102!\n[    5.383923] Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI\n[    5.384903] CPU: 1 UID: 0 PID: 138 Comm: poc_put_cmsg Not tainted 6.12.57 #7\n[    5.384903] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\n[    5.384903] RIP: 0010:usercopy_abort+0x6c/0x80\n[    5.384903] Code: 1a 86 51 48 c7 c2 40 15 1a 86 41 52 48 c7 c7 c0 15 1a 86 48 0f 45 d6 48 c7 c6 80 15 1a 86 48 89 c1 49 0f 45 f3 e8 84 27 88 ff \u003c0f\u003e 0b 490\n[    5.384903] RSP: 0018:ffffc900006f77a8 EFLAGS: 00010246\n[    5.384903] RAX: 000000000000006f RBX: ffff88800f0ad2a8 RCX: 1ffffffff0f72e74\n[    5.384903] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff87b973a0\n[    5.384903] RBP: 0000000000000010 R08: 0000000000000000 R09: fffffbfff0f72e74\n[    5.384903] R10: 0000000000000003 R11: 79706f6372657375 R12: 0000000000000001\n[    5.384903] R13: ffff88800f0ad2b8 R14: ffffea00003c2b40 R15: ffffea00003c2b00\n[    5.384903] FS:  0000000011bc4380(0000) GS:ffff8880bf100000(0000) knlGS:0000000000000000\n[    5.384903] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[    5.384903] CR2: 000056aa3b8e5fe4 CR3: 000000000ea26004 CR4: 0000000000770ef0\n[    5.384903] PKRU: 55555554\n[    5.384903] Call Trace:\n[    5.384903]  \u003cTASK\u003e\n[    5.384903]  __check_heap_object+0x9a/0xd0\n[    5.384903]  __check_object_size+0x46c/0x690\n[    5.384903]  put_cmsg+0x129/0x5e0\n[    5.384903]  sock_recv_errqueue+0x22f/0x380\n[    5.384903]  tls_sw_recvmsg+0x7ed/0x1960\n[    5.384903]  ? srso_alias_return_thunk+0x5/0xfbef5\n[    5.384903]  ? schedule+0x6d/0x270\n[    5.384903]  ? srso_alias_return_thunk+0x5/0xfbef5\n[    5.384903]  ? mutex_unlock+0x81/0xd0\n[    5.384903]  ? __pfx_mutex_unlock+0x10/0x10\n[    5.384903]  ? __pfx_tls_sw_recvmsg+0x10/0x10\n[    5.384903]  ? _raw_spin_lock_irqsave+0x8f/0xf0\n[    5.384903]  ? _raw_read_unlock_irqrestore+0x20/0x40\n[    5.384903]  ? srso_alias_return_thunk+0x5/0xfbef5\n\nThe crash offset 296 corresponds to skb2-\u003ecb within skbuff_fclones:\n  - sizeof(struct sk_buff) = 232 - offsetof(struct sk_buff, cb) = 40 -\n  offset of skb2.cb in fclones = 232 + 40 = 272 - crash offset 296 =\n  272 + 24 (inside sock_exterr_skb.ee)\n\nThis patch uses a local stack variable as a bounce buffer to avoid the hardened usercopy check failure.\n\n[1] https://elixir.bootlin.com/linux/v6.12.62/source/net/ipv4/tcp.c#L885\n[2] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5104\n[3] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5566\n[4] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5491\n[5] https://elixir.bootlin.com/linux/v6.12.62/source/mm/slub.c#L5719",
  "id": "GHSA-rgj2-xq4c-hrvm",
  "modified": "2026-01-21T15:31:16Z",
  "published": "2026-01-21T15:31:16Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-22977"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/005671c60fcf1dbdb8bddf12a62568fd5e4ec391"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2a71a1a8d0ed718b1c7a9ac61f07e5755c47ae20"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/582a5e922a9652fcbb7d0165c95d5b20aa37575d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/88dd6be7ebb3153b662c2cebcb06e032a92857f5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8c6901aa29626e35045130bac09b75f791acca85"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c655d2167bf014d4c61b4faeca59b60ff9b9f6b1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e00b169eaac5f7cdbf710c354c8fa76d02009115"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-22977 (GCVE-0-2026-22977)

Vulnerability from cvelistv5 – Published: 2026-01-21 13:08 – Updated: 2026-01-21 13:08

Title

net: sock: fix hardened usercopy panic in sock_recv_errqueue

Summary

In the Linux kernel, the following vulnerability has been resolved: net: sock: fix hardened usercopy panic in sock_recv_errqueue skbuff_fclone_cache was created without defining a usercopy region, [1] unlike skbuff_head_cache which properly whitelists the cb[] field. [2] This causes a usercopy BUG() when CONFIG_HARDENED_USERCOPY is enabled and the kernel attempts to copy sk_buff.cb data to userspace via sock_recv_errqueue() -> put_cmsg(). The crash occurs when: 1. TCP allocates an skb using alloc_skb_fclone() (from skbuff_fclone_cache) [1] 2. The skb is cloned via skb_clone() using the pre-allocated fclone [3] 3. The cloned skb is queued to sk_error_queue for timestamp reporting 4. Userspace reads the error queue via recvmsg(MSG_ERRQUEUE) 5. sock_recv_errqueue() calls put_cmsg() to copy serr->ee from skb->cb [4] 6. __check_heap_object() fails because skbuff_fclone_cache has no usercopy whitelist [5] When cloned skbs allocated from skbuff_fclone_cache are used in the socket error queue, accessing the sock_exterr_skb structure in skb->cb via put_cmsg() triggers a usercopy hardening violation: [ 5.379589] usercopy: Kernel memory exposure attempt detected from SLUB object 'skbuff_fclone_cache' (offset 296, size 16)! [ 5.382796] kernel BUG at mm/usercopy.c:102! [ 5.383923] Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI [ 5.384903] CPU: 1 UID: 0 PID: 138 Comm: poc_put_cmsg Not tainted 6.12.57 #7 [ 5.384903] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 5.384903] RIP: 0010:usercopy_abort+0x6c/0x80 [ 5.384903] Code: 1a 86 51 48 c7 c2 40 15 1a 86 41 52 48 c7 c7 c0 15 1a 86 48 0f 45 d6 48 c7 c6 80 15 1a 86 48 89 c1 49 0f 45 f3 e8 84 27 88 ff <0f> 0b 490 [ 5.384903] RSP: 0018:ffffc900006f77a8 EFLAGS: 00010246 [ 5.384903] RAX: 000000000000006f RBX: ffff88800f0ad2a8 RCX: 1ffffffff0f72e74 [ 5.384903] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff87b973a0 [ 5.384903] RBP: 0000000000000010 R08: 0000000000000000 R09: fffffbfff0f72e74 [ 5.384903] R10: 0000000000000003 R11: 79706f6372657375 R12: 0000000000000001 [ 5.384903] R13: ffff88800f0ad2b8 R14: ffffea00003c2b40 R15: ffffea00003c2b00 [ 5.384903] FS: 0000000011bc4380(0000) GS:ffff8880bf100000(0000) knlGS:0000000000000000 [ 5.384903] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 5.384903] CR2: 000056aa3b8e5fe4 CR3: 000000000ea26004 CR4: 0000000000770ef0 [ 5.384903] PKRU: 55555554 [ 5.384903] Call Trace: [ 5.384903] <TASK> [ 5.384903] __check_heap_object+0x9a/0xd0 [ 5.384903] __check_object_size+0x46c/0x690 [ 5.384903] put_cmsg+0x129/0x5e0 [ 5.384903] sock_recv_errqueue+0x22f/0x380 [ 5.384903] tls_sw_recvmsg+0x7ed/0x1960 [ 5.384903] ? srso_alias_return_thunk+0x5/0xfbef5 [ 5.384903] ? schedule+0x6d/0x270 [ 5.384903] ? srso_alias_return_thunk+0x5/0xfbef5 [ 5.384903] ? mutex_unlock+0x81/0xd0 [ 5.384903] ? __pfx_mutex_unlock+0x10/0x10 [ 5.384903] ? __pfx_tls_sw_recvmsg+0x10/0x10 [ 5.384903] ? _raw_spin_lock_irqsave+0x8f/0xf0 [ 5.384903] ? _raw_read_unlock_irqrestore+0x20/0x40 [ 5.384903] ? srso_alias_return_thunk+0x5/0xfbef5 The crash offset 296 corresponds to skb2->cb within skbuff_fclones: - sizeof(struct sk_buff) = 232 - offsetof(struct sk_buff, cb) = 40 - offset of skb2.cb in fclones = 232 + 40 = 272 - crash offset 296 = 272 + 24 (inside sock_exterr_skb.ee) This patch uses a local stack variable as a bounce buffer to avoid the hardened usercopy check failure. [1] https://elixir.bootlin.com/linux/v6.12.62/source/net/ipv4/tcp.c#L885 [2] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5104 [3] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5566 [4] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5491 [5] https://elixir.bootlin.com/linux/v6.12.62/source/mm/slub.c#L5719

Severity ?

No CVSS data available.

Assigner

Linux

References

URL

Tags

	https://git.kernel.org/stable/c/88dd6be7ebb3153b6…
	https://git.kernel.org/stable/c/c655d2167bf014d4c…
	https://git.kernel.org/stable/c/8c6901aa29626e350…
	https://git.kernel.org/stable/c/582a5e922a9652fcb…
	https://git.kernel.org/stable/c/005671c60fcf1dbdb…
	https://git.kernel.org/stable/c/e00b169eaac5f7cdb…
	https://git.kernel.org/stable/c/2a71a1a8d0ed718b1…

Impacted products

Vendor

Product

Version

Linux

Affected: 6d07d1cd300f4c7e16005f881fea388164999cc8 , < 88dd6be7ebb3153b662c2cebcb06e032a92857f5 (git)
Affected: 6d07d1cd300f4c7e16005f881fea388164999cc8 , < c655d2167bf014d4c61b4faeca59b60ff9b9f6b1 (git)
Affected: 6d07d1cd300f4c7e16005f881fea388164999cc8 , < 8c6901aa29626e35045130bac09b75f791acca85 (git)
Affected: 6d07d1cd300f4c7e16005f881fea388164999cc8 , < 582a5e922a9652fcbb7d0165c95d5b20aa37575d (git)
Affected: 6d07d1cd300f4c7e16005f881fea388164999cc8 , < 005671c60fcf1dbdb8bddf12a62568fd5e4ec391 (git)
Affected: 6d07d1cd300f4c7e16005f881fea388164999cc8 , < e00b169eaac5f7cdbf710c354c8fa76d02009115 (git)
Affected: 6d07d1cd300f4c7e16005f881fea388164999cc8 , < 2a71a1a8d0ed718b1c7a9ac61f07e5755c47ae20 (git)

Linux

Affected: 4.16
Unaffected: 0 , < 4.16 (semver)
Unaffected: 5.10.248 , ≤ 5.10.* (semver)
Unaffected: 5.15.198 , ≤ 5.15.* (semver)
Unaffected: 6.1.161 , ≤ 6.1.* (semver)
Unaffected: 6.6.121 , ≤ 6.6.* (semver)
Unaffected: 6.12.66 , ≤ 6.12.* (semver)
Unaffected: 6.18.6 , ≤ 6.18.* (semver)
Unaffected: 6.19-rc5 , ≤ * (original_commit_for_fix)

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JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/core/sock.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "88dd6be7ebb3153b662c2cebcb06e032a92857f5",
              "status": "affected",
              "version": "6d07d1cd300f4c7e16005f881fea388164999cc8",
              "versionType": "git"
            },
            {
              "lessThan": "c655d2167bf014d4c61b4faeca59b60ff9b9f6b1",
              "status": "affected",
              "version": "6d07d1cd300f4c7e16005f881fea388164999cc8",
              "versionType": "git"
            },
            {
              "lessThan": "8c6901aa29626e35045130bac09b75f791acca85",
              "status": "affected",
              "version": "6d07d1cd300f4c7e16005f881fea388164999cc8",
              "versionType": "git"
            },
            {
              "lessThan": "582a5e922a9652fcbb7d0165c95d5b20aa37575d",
              "status": "affected",
              "version": "6d07d1cd300f4c7e16005f881fea388164999cc8",
              "versionType": "git"
            },
            {
              "lessThan": "005671c60fcf1dbdb8bddf12a62568fd5e4ec391",
              "status": "affected",
              "version": "6d07d1cd300f4c7e16005f881fea388164999cc8",
              "versionType": "git"
            },
            {
              "lessThan": "e00b169eaac5f7cdbf710c354c8fa76d02009115",
              "status": "affected",
              "version": "6d07d1cd300f4c7e16005f881fea388164999cc8",
              "versionType": "git"
            },
            {
              "lessThan": "2a71a1a8d0ed718b1c7a9ac61f07e5755c47ae20",
              "status": "affected",
              "version": "6d07d1cd300f4c7e16005f881fea388164999cc8",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/core/sock.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.16"
            },
            {
              "lessThan": "4.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.248",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.198",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.161",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.121",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.66",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.19-rc5",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.248",
                  "versionStartIncluding": "4.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.198",
                  "versionStartIncluding": "4.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.161",
                  "versionStartIncluding": "4.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.121",
                  "versionStartIncluding": "4.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.66",
                  "versionStartIncluding": "4.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.6",
                  "versionStartIncluding": "4.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19-rc5",
                  "versionStartIncluding": "4.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: sock: fix hardened usercopy panic in sock_recv_errqueue\n\nskbuff_fclone_cache was created without defining a usercopy region,\n[1] unlike skbuff_head_cache which properly whitelists the cb[] field.\n[2] This causes a usercopy BUG() when CONFIG_HARDENED_USERCOPY is\nenabled and the kernel attempts to copy sk_buff.cb data to userspace\nvia sock_recv_errqueue() -\u003e put_cmsg().\n\nThe crash occurs when: 1. TCP allocates an skb using alloc_skb_fclone()\n   (from skbuff_fclone_cache) [1]\n2. The skb is cloned via skb_clone() using the pre-allocated fclone\n[3] 3. The cloned skb is queued to sk_error_queue for timestamp\nreporting 4. Userspace reads the error queue via recvmsg(MSG_ERRQUEUE)\n5. sock_recv_errqueue() calls put_cmsg() to copy serr-\u003eee from skb-\u003ecb\n[4] 6. __check_heap_object() fails because skbuff_fclone_cache has no\n   usercopy whitelist [5]\n\nWhen cloned skbs allocated from skbuff_fclone_cache are used in the\nsocket error queue, accessing the sock_exterr_skb structure in skb-\u003ecb\nvia put_cmsg() triggers a usercopy hardening violation:\n\n[    5.379589] usercopy: Kernel memory exposure attempt detected from SLUB object \u0027skbuff_fclone_cache\u0027 (offset 296, size 16)!\n[    5.382796] kernel BUG at mm/usercopy.c:102!\n[    5.383923] Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI\n[    5.384903] CPU: 1 UID: 0 PID: 138 Comm: poc_put_cmsg Not tainted 6.12.57 #7\n[    5.384903] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\n[    5.384903] RIP: 0010:usercopy_abort+0x6c/0x80\n[    5.384903] Code: 1a 86 51 48 c7 c2 40 15 1a 86 41 52 48 c7 c7 c0 15 1a 86 48 0f 45 d6 48 c7 c6 80 15 1a 86 48 89 c1 49 0f 45 f3 e8 84 27 88 ff \u003c0f\u003e 0b 490\n[    5.384903] RSP: 0018:ffffc900006f77a8 EFLAGS: 00010246\n[    5.384903] RAX: 000000000000006f RBX: ffff88800f0ad2a8 RCX: 1ffffffff0f72e74\n[    5.384903] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff87b973a0\n[    5.384903] RBP: 0000000000000010 R08: 0000000000000000 R09: fffffbfff0f72e74\n[    5.384903] R10: 0000000000000003 R11: 79706f6372657375 R12: 0000000000000001\n[    5.384903] R13: ffff88800f0ad2b8 R14: ffffea00003c2b40 R15: ffffea00003c2b00\n[    5.384903] FS:  0000000011bc4380(0000) GS:ffff8880bf100000(0000) knlGS:0000000000000000\n[    5.384903] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[    5.384903] CR2: 000056aa3b8e5fe4 CR3: 000000000ea26004 CR4: 0000000000770ef0\n[    5.384903] PKRU: 55555554\n[    5.384903] Call Trace:\n[    5.384903]  \u003cTASK\u003e\n[    5.384903]  __check_heap_object+0x9a/0xd0\n[    5.384903]  __check_object_size+0x46c/0x690\n[    5.384903]  put_cmsg+0x129/0x5e0\n[    5.384903]  sock_recv_errqueue+0x22f/0x380\n[    5.384903]  tls_sw_recvmsg+0x7ed/0x1960\n[    5.384903]  ? srso_alias_return_thunk+0x5/0xfbef5\n[    5.384903]  ? schedule+0x6d/0x270\n[    5.384903]  ? srso_alias_return_thunk+0x5/0xfbef5\n[    5.384903]  ? mutex_unlock+0x81/0xd0\n[    5.384903]  ? __pfx_mutex_unlock+0x10/0x10\n[    5.384903]  ? __pfx_tls_sw_recvmsg+0x10/0x10\n[    5.384903]  ? _raw_spin_lock_irqsave+0x8f/0xf0\n[    5.384903]  ? _raw_read_unlock_irqrestore+0x20/0x40\n[    5.384903]  ? srso_alias_return_thunk+0x5/0xfbef5\n\nThe crash offset 296 corresponds to skb2-\u003ecb within skbuff_fclones:\n  - sizeof(struct sk_buff) = 232 - offsetof(struct sk_buff, cb) = 40 -\n  offset of skb2.cb in fclones = 232 + 40 = 272 - crash offset 296 =\n  272 + 24 (inside sock_exterr_skb.ee)\n\nThis patch uses a local stack variable as a bounce buffer to avoid the hardened usercopy check failure.\n\n[1] https://elixir.bootlin.com/linux/v6.12.62/source/net/ipv4/tcp.c#L885\n[2] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5104\n[3] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5566\n[4] https://elixir.bootlin.com/linux/v6.12.62/source/net/core/skbuff.c#L5491\n[5] https://elixir.bootlin.com/linux/v6.12.62/source/mm/slub.c#L5719"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-01-21T13:08:54.858Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/88dd6be7ebb3153b662c2cebcb06e032a92857f5"
        },
        {
          "url": "https://git.kernel.org/stable/c/c655d2167bf014d4c61b4faeca59b60ff9b9f6b1"
        },
        {
          "url": "https://git.kernel.org/stable/c/8c6901aa29626e35045130bac09b75f791acca85"
        },
        {
          "url": "https://git.kernel.org/stable/c/582a5e922a9652fcbb7d0165c95d5b20aa37575d"
        },
        {
          "url": "https://git.kernel.org/stable/c/005671c60fcf1dbdb8bddf12a62568fd5e4ec391"
        },
        {
          "url": "https://git.kernel.org/stable/c/e00b169eaac5f7cdbf710c354c8fa76d02009115"
        },
        {
          "url": "https://git.kernel.org/stable/c/2a71a1a8d0ed718b1c7a9ac61f07e5755c47ae20"
        }
      ],
      "title": "net: sock: fix hardened usercopy panic in sock_recv_errqueue",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-22977",
    "datePublished": "2026-01-21T13:08:54.858Z",
    "dateReserved": "2026-01-13T15:37:45.935Z",
    "dateUpdated": "2026-01-21T13:08:54.858Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-RGJ2-XQ4C-HRVM

CVE-2026-22977 (GCVE-0-2026-22977)

Tags

Sightings

Nomenclature