CVE-2026-53034
Estado: AnalizadaMedia (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
bpf, sockmap: Fix af_unix null-ptr-deref in proto update
unix_stream_connect() sets sk_state (`WRITE_ONCE(sk->sk_state, TCP_ESTABLISHED)`) _before_ it assigns a peer (`unix_peer(sk) = newsk`). sk_state == TCP_ESTABLISHED makes sock_map_sk_state_allowed() believe that socket is properly set up, which would include having a defined peer. IOW, there's a window when unix_stream_bpf_update_proto() can be called on socket which still has unix_peer(sk) == NULL.
Initial idea was to move peer assignment _before_ the sk_state update[1], but that involved an additional memory barrier, and changing the hot path was rejected.
Leer descripción completaMostrar menos
Then a NULL check during proto update in unix_stream_bpf_update_proto() was considered[2], but the follow-up discussion[3] focused on the root cause, i.e. sockmap update taking a wrong lock. Or, more specifically, missing unix_state_lock()[4]. In the end it was concluded that teaching sockmap about the af_unix locking would be unnecessarily complex[5]. Complexity aside, since BPF_PROG_TYPE_SCHED_CLS and BPF_PROG_TYPE_SCHED_ACT are allowed to update sockmaps, sock_map_update_elem() taking the unix lock, as it is currently implemented in unix_state_lock(): spin_lock(&unix_sk(s)->lock), would be problematic. unix_state_lock() taken in a process context, followed by a softirq-context TC BPF program attempting to take the same spinlock -- deadlock[6]. This way we circled back to the peer check idea[2].
[1]: https://lore.kernel.org/netdev/ba5c50aa-1df4-40c2-ab33-a72022c5a32e@rbox.co/ [2]: https://lore.kernel.org/netdev/20240610174906.32921-1-kuniyu@amazon.com/ [3]: https://lore.kernel.org/netdev/7603c0e6-cd5b-452b-b710-73b64bd9de26@linux.dev/ [4]: https://lore.kernel.org/netdev/CAAVpQUA+8GL_j63CaKb8hbxoL21izD58yr1NvhOhU=j+35+3og@mail.gmail.com/ [5]: https://lore.kernel.org/bpf/CAAVpQUAHijOMext28Gi10dSLuMzGYh+jK61Ujn+fZ-wvcODR2A@mail.gmail.com/ [6]: https://lore.kernel.org/bpf/dd043c69-4d03-46fe-8325-8f97101435cf@linux.dev/
Summary of scenarios where af_unix/stream connect() may race a sockmap update:
1. connect() vs. bpf(BPF_MAP_UPDATE_ELEM), i.e. sock_map_update_elem_sys()
2. connect() vs BPF program doing update
---truncated---
Detalles técnicos trazas, registros y código del informe original
CPU0 bpf CPU1 connect
-------- ------------
WRITE_ONCE(sk->sk_state, TCP_ESTABLISHED)
sock_map_sk_state_allowed(sk)
...
sk_pair = unix_peer(sk)
sock_hold(sk_pair)
sock_hold(newsk)
smp_mb__after_atomic()
unix_peer(sk) = newsk
BUG: kernel NULL pointer dereference, address: 0000000000000080
RIP: 0010:unix_stream_bpf_update_proto+0xa0/0x1b0
Call Trace:
sock_map_link+0x564/0x8b0
sock_map_update_common+0x6e/0x340
sock_map_update_elem_sys+0x17d/0x240
__sys_bpf+0x26db/0x3250
__x64_sys_bpf+0x21/0x30
do_syscall_64+0x6b/0x3a0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Implemented NULL check is sufficient. Once assigned, socket peer won't
be released until socket fd is released. And that's not an issue because
sock_map_update_elem_sys() bumps fd refcnf.
Update restricted per verifier.c:may_update_sockmap() to
BPF_PROG_TYPE_TRACING/BPF_TRACE_ITER
BPF_PROG_TYPE_SOCK_OPS (bpf_sock_map_update() only)
BPF_PROG_TYPE_SOCKET_FILTER
BPF_PROG_TYPE_SCHED_CLS
BPF_PROG_TYPE_SCHED_ACT
BPF_PROG_TYPE_XDP
BPF_PROG_TYPE_SK_REUSEPORT
BPF_PROG_TYPE_FLOW_DISSECTOR
BPF_PROG_TYPE_SK_LOOKUP
Plus one more race to consider:
CPU0 bpf CPU1 connect
-------- ------------
WRITE_ONCE(sk->sk_state, TCP_ESTABLISHED)
sock_map_sk_state_allowed(sk)
sock_hold(newsk)
smp_mb__after_atomic()CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 5.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.13%
- Percentil entre todas las CVEs puntuadas: 2
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
CWE
- CWE-476
Referencias
- https://git.kernel.org/stable/c/041eb6348d73ee5e15fc8161f1eac5a6e8289ca0
- https://git.kernel.org/stable/c/37bfcd164161b47d00b1c3bd20adc816a6977ce0
- https://git.kernel.org/stable/c/4913c94a3adcdbb64c552110c0c243cb1fdbb317
- https://git.kernel.org/stable/c/75b7d3b3f8bd4e59eb3af1b11a43c64c0c2db6f4
- https://git.kernel.org/stable/c/a94d3dd78ee8b63e6b8ad629081c952c93ee5a10
- https://git.kernel.org/stable/c/dca38b7734d2ea00af4818ff3ae836fab33d5d5a
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-53034",
"cveTags": [],
"metrics": {
"cvssMetricV31": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 5.5,
"attackVector": "LOCAL",
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"integrityImpact": "NONE",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "NONE"
},
"impactScore": 3.6,
"exploitabilityScore": 1.8
}
]
},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "c63829182c37c2d6d0608976d15fa61ebebe9e6b",
"lessThan": "75b7d3b3f8bd4e59eb3af1b11a43c64c0c2db6f4",
"versionType": "git"
},
{
"status": "affected",
"version": "c63829182c37c2d6d0608976d15fa61ebebe9e6b",
"lessThan": "a94d3dd78ee8b63e6b8ad629081c952c93ee5a10",
"versionType": "git"
},
{
"status": "affected",
"version": "c63829182c37c2d6d0608976d15fa61ebebe9e6b",
"lessThan": "4913c94a3adcdbb64c552110c0c243cb1fdbb317",
"versionType": "git"
},
{
"status": "affected",
"version": "c63829182c37c2d6d0608976d15fa61ebebe9e6b",
"lessThan": "041eb6348d73ee5e15fc8161f1eac5a6e8289ca0",
"versionType": "git"
},
{
"status": "affected",
"version": "c63829182c37c2d6d0608976d15fa61ebebe9e6b",
"lessThan": "37bfcd164161b47d00b1c3bd20adc816a6977ce0",
"versionType": "git"
},
{
"status": "affected",
"version": "c63829182c37c2d6d0608976d15fa61ebebe9e6b",
"lessThan": "dca38b7734d2ea00af4818ff3ae836fab33d5d5a",
"versionType": "git"
}
],
"programFiles": [
"net/unix/unix_bpf.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.15"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.15",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.1.175",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.141",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.91",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.33",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.10",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/unix/unix_bpf.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-06-24T17:17:14.843",
"references": [
{
"url": "https://git.kernel.org/stable/c/041eb6348d73ee5e15fc8161f1eac5a6e8289ca0",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/37bfcd164161b47d00b1c3bd20adc816a6977ce0",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/4913c94a3adcdbb64c552110c0c243cb1fdbb317",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/75b7d3b3f8bd4e59eb3af1b11a43c64c0c2db6f4",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/a94d3dd78ee8b63e6b8ad629081c952c93ee5a10",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/dca38b7734d2ea00af4818ff3ae836fab33d5d5a",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Analyzed",
"weaknesses": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"description": [
{
"lang": "en",
"value": "CWE-476"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, sockmap: Fix af_unix null-ptr-deref in proto update\n\nunix_stream_connect() sets sk_state (`WRITE_ONCE(sk->sk_state,\nTCP_ESTABLISHED)`) _before_ it assigns a peer (`unix_peer(sk) = newsk`).\nsk_state == TCP_ESTABLISHED makes sock_map_sk_state_allowed() believe that\nsocket is properly set up, which would include having a defined peer. IOW,\nthere's a window when unix_stream_bpf_update_proto() can be called on\nsocket which still has unix_peer(sk) == NULL.\n\n CPU0 bpf CPU1 connect\n -------- ------------\n\n WRITE_ONCE(sk->sk_state, TCP_ESTABLISHED)\nsock_map_sk_state_allowed(sk)\n...\nsk_pair = unix_peer(sk)\nsock_hold(sk_pair)\n sock_hold(newsk)\n smp_mb__after_atomic()\n unix_peer(sk) = newsk\n\nBUG: kernel NULL pointer dereference, address: 0000000000000080\nRIP: 0010:unix_stream_bpf_update_proto+0xa0/0x1b0\nCall Trace:\n sock_map_link+0x564/0x8b0\n sock_map_update_common+0x6e/0x340\n sock_map_update_elem_sys+0x17d/0x240\n __sys_bpf+0x26db/0x3250\n __x64_sys_bpf+0x21/0x30\n do_syscall_64+0x6b/0x3a0\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nInitial idea was to move peer assignment _before_ the sk_state update[1],\nbut that involved an additional memory barrier, and changing the hot path\nwas rejected.\nThen a NULL check during proto update in unix_stream_bpf_update_proto() was\nconsidered[2], but the follow-up discussion[3] focused on the root cause,\ni.e. sockmap update taking a wrong lock. Or, more specifically, missing\nunix_state_lock()[4].\nIn the end it was concluded that teaching sockmap about the af_unix locking\nwould be unnecessarily complex[5].\nComplexity aside, since BPF_PROG_TYPE_SCHED_CLS and BPF_PROG_TYPE_SCHED_ACT\nare allowed to update sockmaps, sock_map_update_elem() taking the unix\nlock, as it is currently implemented in unix_state_lock():\nspin_lock(&unix_sk(s)->lock), would be problematic. unix_state_lock() taken\nin a process context, followed by a softirq-context TC BPF program\nattempting to take the same spinlock -- deadlock[6].\nThis way we circled back to the peer check idea[2].\n\n[1]: https://lore.kernel.org/netdev/ba5c50aa-1df4-40c2-ab33-a72022c5a32e@rbox.co/\n[2]: https://lore.kernel.org/netdev/20240610174906.32921-1-kuniyu@amazon.com/\n[3]: https://lore.kernel.org/netdev/7603c0e6-cd5b-452b-b710-73b64bd9de26@linux.dev/\n[4]: https://lore.kernel.org/netdev/CAAVpQUA+8GL_j63CaKb8hbxoL21izD58yr1NvhOhU=j+35+3og@mail.gmail.com/\n[5]: https://lore.kernel.org/bpf/CAAVpQUAHijOMext28Gi10dSLuMzGYh+jK61Ujn+fZ-wvcODR2A@mail.gmail.com/\n[6]: https://lore.kernel.org/bpf/dd043c69-4d03-46fe-8325-8f97101435cf@linux.dev/\n\nSummary of scenarios where af_unix/stream connect() may race a sockmap\nupdate:\n\n1. connect() vs. bpf(BPF_MAP_UPDATE_ELEM), i.e. sock_map_update_elem_sys()\n\n Implemented NULL check is sufficient. Once assigned, socket peer won't\n be released until socket fd is released. And that's not an issue because\n sock_map_update_elem_sys() bumps fd refcnf.\n\n2. connect() vs BPF program doing update\n\n Update restricted per verifier.c:may_update_sockmap() to\n\n BPF_PROG_TYPE_TRACING/BPF_TRACE_ITER\n BPF_PROG_TYPE_SOCK_OPS (bpf_sock_map_update() only)\n BPF_PROG_TYPE_SOCKET_FILTER\n BPF_PROG_TYPE_SCHED_CLS\n BPF_PROG_TYPE_SCHED_ACT\n BPF_PROG_TYPE_XDP\n BPF_PROG_TYPE_SK_REUSEPORT\n BPF_PROG_TYPE_FLOW_DISSECTOR\n BPF_PROG_TYPE_SK_LOOKUP\n\n Plus one more race to consider:\n\n CPU0 bpf CPU1 connect\n -------- ------------\n\n WRITE_ONCE(sk->sk_state, TCP_ESTABLISHED)\n sock_map_sk_state_allowed(sk)\n sock_hold(newsk)\n smp_mb__after_atomic()\n \n---truncated---"
}
],
"lastModified": "2026-07-15T14:38:08.400",
"configurations": [
{
"nodes": [
{
"negate": false,
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "9BD4FB16-83D6-4779-9B40-3CF40D134FB1",
"versionEndExcluding": "6.1.175",
"versionStartIncluding": "5.15"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "97A9FFFA-22BB-4D5C-9790-5A2286E392F7",
"versionEndExcluding": "6.6.141",
"versionStartIncluding": "6.2"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "C918746B-DE6F-448F-A93E-A04C5481688D",
"versionEndExcluding": "6.12.91",
"versionStartIncluding": "6.7"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "96D99E49-380D-43AB-BDBA-25C3AD018A9C",
"versionEndExcluding": "6.18.33",
"versionStartIncluding": "6.13"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "A13475D2-59BF-4716-94B5-7C1D239A2CF4",
"versionEndExcluding": "7.0.10",
"versionStartIncluding": "6.19"
}
],
"operator": "OR"
}
]
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}