{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-22977", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-22977", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-01-21T13:08:54.858Z", "updatedAt": "2026-10-19T18:25:25.873Z", "importedAt": "2026-10-24T01:58:02.025Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "net: sock: fix hardened usercopy panic in sock_recv_errqueue", "summary": "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() -> 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->ee from skb->cb\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->cb\nvia put_cmsg() triggers a usercopy hardening violation:\n\n[ 5.379589] usercopy: Kernel memory exposure attempt detected from SLUB object 'skbuff_fclone_cache' (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 <0f> 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] \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->cb 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", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "6d07d1cd300f4c7e16005f881fea388164999cc8", "status": "affected", "versionType": "git", "lessThan": "88dd6be7ebb3153b662c2cebcb06e032a92857f5" }, { "version": "6d07d1cd300f4c7e16005f881fea388164999cc8", "status": "affected", "versionType": "git", "lessThan": "c655d2167bf014d4c61b4faeca59b60ff9b9f6b1" }, { "version": "6d07d1cd300f4c7e16005f881fea388164999cc8", "status": "affected", "versionType": "git", "lessThan": "8c6901aa29626e35045130bac09b75f791acca85" }, { "version": "6d07d1cd300f4c7e16005f881fea388164999cc8", "status": "affected", "versionType": "git", "lessThan": "582a5e922a9652fcbb7d0165c95d5b20aa37575d" }, { "version": "6d07d1cd300f4c7e16005f881fea388164999cc8", "status": "affected", "versionType": "git", "lessThan": "005671c60fcf1dbdb8bddf12a62568fd5e4ec391" }, { "version": "6d07d1cd300f4c7e16005f881fea388164999cc8", "status": "affected", "versionType": "git", "lessThan": "e00b169eaac5f7cdbf710c354c8fa76d02009115" }, { "version": "6d07d1cd300f4c7e16005f881fea388164999cc8", "status": "affected", "versionType": "git", "lessThan": "2a71a1a8d0ed718b1c7a9ac61f07e5755c47ae20" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "4.16", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "4.16" }, { "version": "5.10.248", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.198", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.161", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.121", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.66", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.6", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "6.19", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }