CVE-2026-53191 (GCVE-0-2026-53191)
Vulnerability from cvelistv5
Published
2026-06-25 08:39
Modified
2026-08-05 12:33
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
io_uring/net: inherit IORING_CQE_F_BUF_MORE across bundle recv retries
When a bundle recv retries inside io_recv_finish(), the merge logic OR
the saved cflags from the previous iteration with the cflags returned by
the new iteration:
cflags = req->cqe.flags | (cflags & CQE_F_MASK);
Bits listed in CQE_F_MASK are inherited from the new iteration, and all
other bits (notably IORING_CQE_F_BUFFER and the buffer ID) come from the
saved cflags. Before this change CQE_F_MASK covered only
IORING_CQE_F_SOCK_NONEMPTY and IORING_CQE_F_MORE.
When using provided buffer rings (IOU_PBUF_RING_INC) with incremental
mode, and bundle recv, io_kbuf_inc_commit() can leave the head ring
entry partially consumed, __io_put_kbufs() then sets
IORING_CQE_F_BUF_MORE on the returned cflags so userspace knows the
buffer ID will be reused for subsequent completions.
Because IORING_CQE_F_BUF_MORE was not in CQE_F_MASK, the merge above
silently dropped it whenever the final retry iteration partially
consumed the buffer, and the subsequent req->cqe.flags = cflags &
~CQE_F_MASK save would have left a stale IORING_CQE_F_BUF_MORE in the
carried-over cflags had one been present. Userspace would then
wrongfully advance it ring head past an entry the kernel still uses.
Add IORING_CQE_F_BUF_MORE to CQE_F_MASK so it is both inherited from the
new iteration into the user-visible CQE and stripped from the saved
cflags between iterations.
References
| URL | Tags | |
|---|---|---|
Impacted products
{
"containers": {
"cna": {
"affected": [
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"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"io_uring/net.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"versionType": "git"
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{
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"programFiles": [
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],
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"versions": [
{
"status": "affected",
"version": "6.12"
},
{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.94",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.36",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.0.*",
"status": "unaffected",
"version": "7.0.13",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.94",
"versionStartIncluding": "6.12",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.36",
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/net: inherit IORING_CQE_F_BUF_MORE across bundle recv retries\n\nWhen a bundle recv retries inside io_recv_finish(), the merge logic OR\nthe saved cflags from the previous iteration with the cflags returned by\nthe new iteration:\n cflags = req-\u003ecqe.flags | (cflags \u0026 CQE_F_MASK);\n\nBits listed in CQE_F_MASK are inherited from the new iteration, and all\nother bits (notably IORING_CQE_F_BUFFER and the buffer ID) come from the\nsaved cflags. Before this change CQE_F_MASK covered only\nIORING_CQE_F_SOCK_NONEMPTY and IORING_CQE_F_MORE.\n\nWhen using provided buffer rings (IOU_PBUF_RING_INC) with incremental\nmode, and bundle recv, io_kbuf_inc_commit() can leave the head ring\nentry partially consumed, __io_put_kbufs() then sets\nIORING_CQE_F_BUF_MORE on the returned cflags so userspace knows the\nbuffer ID will be reused for subsequent completions.\n\nBecause IORING_CQE_F_BUF_MORE was not in CQE_F_MASK, the merge above\nsilently dropped it whenever the final retry iteration partially\nconsumed the buffer, and the subsequent req-\u003ecqe.flags = cflags \u0026\n~CQE_F_MASK save would have left a stale IORING_CQE_F_BUF_MORE in the\ncarried-over cflags had one been present. Userspace would then\nwrongfully advance it ring head past an entry the kernel still uses.\n\nAdd IORING_CQE_F_BUF_MORE to CQE_F_MASK so it is both inherited from the\nnew iteration into the user-visible CQE and stripped from the saved\ncflags between iterations."
}
],
"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 vulnerable path is reached through locally submitted io_uring receive operations with buffer selection and bundle recv; a remote peer can influence socket data, but cannot select these io_uring flags or register the buffer ring by itself.\nAC:L - The trigger is deterministic once the attacker controls the io_uring setup, buffer sizes, and socket data pattern; no uncontrolled race or rare kernel state is required.\nPR:L - A basic unprivileged local user can normally create an io_uring instance, register an incremental provided-buffer ring, and submit IORING_OP_RECV, absent non-default sysctl or LSM restrictions.\nUI:N - No separate victim interaction is required after the attacker submits the crafted io_uring operations and supplies socket data.\nS:U - This is a kernel/io_uring buffer ownership bug and does not cross a VM, IOMMU, or other separate security authority boundary.\nC:H - The dropped BUF_MORE flag can make userspace reclaim a buffer that the kernel will continue to use, creating a use-after-recycle style memory corruption primitive in an affected io_uring consumer.\nI:H - The stale ownership state can cause later kernel receives to write attacker-controlled socket data into memory that the application has legitimately reused, which is a high-impact corruption primitive.\nA:H - The same buffer reuse corruption can crash or destabilize an affected io_uring receiver, and repeated triggering is under attacker control once the vulnerable operation pattern is in use."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-05T12:33:57.520Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/f40570fda3f3a1f96aeaa4aef665ba274b2810b5"
},
{
"url": "https://git.kernel.org/stable/c/0bbc9481f970b0b4ddb08cfa464db1cc93b74b56"
},
{
"url": "https://git.kernel.org/stable/c/4973232a67e4137ab9399f504f7f2bdd847f96d2"
},
{
"url": "https://git.kernel.org/stable/c/ed46f39c47eb5530a9c161481a2080d3a869cfaf"
}
],
"title": "io_uring/net: inherit IORING_CQE_F_BUF_MORE across bundle recv retries",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-53191",
"datePublished": "2026-06-25T08:39:03.052Z",
"dateReserved": "2026-06-09T07:44:35.390Z",
"dateUpdated": "2026-08-05T12:33:57.520Z",
"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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