CVE-2026-74634 (GCVE-0-2026-74634)
Vulnerability from cvelistv5
Published
2026-08-22 15:32
Modified
2026-08-25 05:40
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
ring-buffer: Prevent subbuf order change when resizing is disabled
Because ring_buffer_subbuf_order_set() frees buffer pages, we can't
allow it when resizing is disabled. A non-consuming reader is at risk of
use-after-free (rb_advance_iter()).
Return -EBUSY on resize_disabled, matching ring_buffer_resize()
behaviour.
References
| URL | Tags | |
|---|---|---|
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"kernel/trace/ring_buffer.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"version": "f9b94daa542a8d2532f0930f01cd9aec2d19621b",
"versionType": "git"
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{
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"status": "affected",
"version": "f9b94daa542a8d2532f0930f01cd9aec2d19621b",
"versionType": "git"
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"version": "f9b94daa542a8d2532f0930f01cd9aec2d19621b",
"versionType": "git"
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{
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"versionType": "git"
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},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"kernel/trace/ring_buffer.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.8"
},
{
"lessThan": "6.8",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.104",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.45",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.9",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.104",
"versionStartIncluding": "6.8",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.45",
"versionStartIncluding": "6.8",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.8",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "6.8",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Prevent subbuf order change when resizing is disabled\n\nBecause ring_buffer_subbuf_order_set() frees buffer pages, we can\u0027t\nallow it when resizing is disabled. A non-consuming reader is at risk of\nuse-after-free (rb_advance_iter()).\n\nReturn -EBUSY on resize_disabled, matching ring_buffer_resize()\nbehaviour."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The bug is reached only via local tracefs operations: write() to buffer_subbuf_size_kb (buffer_subbuf_size_write) while a non-consuming ring_buffer_read_start() iterator is active from reading trace/per_cpu/cpuN/trace. No network, adjacent-radio, or physical-device path reaches ring_buffer_subbuf_order_set().\nAC:L - The attacker controls both sides: one thread holds trace open for read (sets resize_disabled via ring_buffer_read_start) while another writes buffer_subbuf_size_kb to free pages still referenced by iter-\u003ehead_page. rb_advance_iter()/rb_inc_iter then dereferences freed memory; the race is reliably retried.\nPR:L - tracing_check_open_get_tr() enforces only LOCKDOWN_TRACEFS and DAC with no capability check. tracefs buffer_subbuf_size_kb and trace are mode 0640 and are routinely delegated via gid=/mode= to tracing-group members on Android/Perfetto, ChromeOS, and developer systems, matching prior CNA tracefs UAF scores (CVE-2024-50207, CVE-2025-38101).\nUI:N - Exploitation uses the attacker\u0027s own tracefs file descriptors and threads (open trace for read, write buffer_subbuf_size_kb). No separate victim mount, click, or configuration action is required beyond the attacker holding tracefs access.\nS:U - The use-after-free corrupts kernel ring-buffer heap pages and metadata within the same OS security authority. It enables local privilege escalation but does not cross VM, IOMMU, container, or hardware trust boundaries.\nC:H - ring_buffer_subbuf_order_set() frees buffer_page data pages while iterators retain head_page pointers; rb_iter_head_event() memcpy() and rb_inc_iter() read iter-\u003ehead_page-\u003epage after free_pages(), leaking recycled kernel heap contents to userspace through trace reads.\nI:H - Freed sub-buffer pages and buffer_page structures can be reused while iterators and splice paths still perform stores and list operations on them. This UAF heap corruption is exploitable for arbitrary kernel writes and control-flow hijack, not merely a crash.\nA:H - Concurrent page frees with active iterators corrupt ring-buffer lists and cause use-after-free dereferences in rb_advance_iter(), producing kernel oopses/panics. syzbot reported this failure mode and the attacker can retrigger it at will."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-25T05:40:58.185Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/b45b91db41379ee5fb36c187d6d7c37b725cbe8e"
},
{
"url": "https://git.kernel.org/stable/c/62978cf6347972c04130e4e841ba404504d92b32"
},
{
"url": "https://git.kernel.org/stable/c/7568e9e717e7540bd05bcc007f5d76fcaff3cdff"
},
{
"url": "https://git.kernel.org/stable/c/bf98d7b0d5a99991e47e66cee4eb1d3fa514be97"
}
],
"title": "ring-buffer: Prevent subbuf order change when resizing is disabled",
"x_generator": {
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}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74634",
"datePublished": "2026-08-22T15:32:14.547Z",
"dateReserved": "2026-08-15T05:44:03.922Z",
"dateUpdated": "2026-08-25T05:40:58.185Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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