CVE-2026-31774 (GCVE-0-2026-31774)
Vulnerability from cvelistv5
Published
2026-05-01 14:15
Modified
2026-08-05 12:25
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
io_uring/net: fix slab-out-of-bounds read in io_bundle_nbufs()
sqe->len is __u32 but gets stored into sr->len which is int. When
userspace passes sqe->len values exceeding INT_MAX (e.g. 0xFFFFFFFF),
sr->len overflows to a negative value. This negative value propagates
through the bundle recv/send path:
1. io_recv(): sel.val = sr->len (ssize_t gets -1)
2. io_recv_buf_select(): arg.max_len = sel->val (size_t gets
0xFFFFFFFFFFFFFFFF)
3. io_ring_buffers_peek(): buf->len is not clamped because max_len
is astronomically large
4. iov[].iov_len = 0xFFFFFFFF flows into io_bundle_nbufs()
5. io_bundle_nbufs(): min_t(int, 0xFFFFFFFF, ret) yields -1,
causing ret to increase instead of decrease, creating an
infinite loop that reads past the allocated iov[] array
This results in a slab-out-of-bounds read in io_bundle_nbufs() from
the kmalloc-64 slab, as nbufs increments past the allocated iovec
entries.
BUG: KASAN: slab-out-of-bounds in io_bundle_nbufs+0x128/0x160
Read of size 8 at addr ffff888100ae05c8 by task exp/145
Call Trace:
io_bundle_nbufs+0x128/0x160
io_recv_finish+0x117/0xe20
io_recv+0x2db/0x1160
Fix this by rejecting negative sr->len values early in both
io_sendmsg_prep() and io_recvmsg_prep(). Since sqe->len is __u32,
any value > INT_MAX indicates overflow and is not a valid length.
References
| URL | Tags | |
|---|---|---|
Impacted products
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"status": "unaffected",
"version": "6.12.81",
"versionType": "semver"
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{
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"status": "unaffected",
"version": "6.18.22",
"versionType": "semver"
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{
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"status": "unaffected",
"version": "6.19.12",
"versionType": "semver"
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{
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"version": "7.0",
"versionType": "original_commit_for_fix"
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],
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],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/net: fix slab-out-of-bounds read in io_bundle_nbufs()\n\nsqe-\u003elen is __u32 but gets stored into sr-\u003elen which is int. When\nuserspace passes sqe-\u003elen values exceeding INT_MAX (e.g. 0xFFFFFFFF),\nsr-\u003elen overflows to a negative value. This negative value propagates\nthrough the bundle recv/send path:\n\n 1. io_recv(): sel.val = sr-\u003elen (ssize_t gets -1)\n 2. io_recv_buf_select(): arg.max_len = sel-\u003eval (size_t gets\n 0xFFFFFFFFFFFFFFFF)\n 3. io_ring_buffers_peek(): buf-\u003elen is not clamped because max_len\n is astronomically large\n 4. iov[].iov_len = 0xFFFFFFFF flows into io_bundle_nbufs()\n 5. io_bundle_nbufs(): min_t(int, 0xFFFFFFFF, ret) yields -1,\n causing ret to increase instead of decrease, creating an\n infinite loop that reads past the allocated iov[] array\n\nThis results in a slab-out-of-bounds read in io_bundle_nbufs() from\nthe kmalloc-64 slab, as nbufs increments past the allocated iovec\nentries.\n\n BUG: KASAN: slab-out-of-bounds in io_bundle_nbufs+0x128/0x160\n Read of size 8 at addr ffff888100ae05c8 by task exp/145\n Call Trace:\n io_bundle_nbufs+0x128/0x160\n io_recv_finish+0x117/0xe20\n io_recv+0x2db/0x1160\n\nFix this by rejecting negative sr-\u003elen values early in both\nio_sendmsg_prep() and io_recvmsg_prep(). Since sqe-\u003elen is __u32,\nany value \u003e INT_MAX indicates overflow and is not a valid length."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.1,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
"version": "3.1"
},
"scenarios": [
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"value": "AV:L - The vulnerable path is reached through local io_uring syscalls by submitting IORING_OP_RECV/SEND with provided buffer selection and bundle flags.\nAC:L - An attacker controls the SQE length, buffer ring contents, and socket traffic needed to trigger the slab out-of-bounds read; no race or external condition is required.\nPR:L - A basic unprivileged local user can normally create an io_uring instance and use ordinary sockets and provided buffer rings, absent non-default sysctl/LSM restrictions.\nUI:N - No victim action is needed after the attacker has local execution; the attacker submits the crafted io_uring operations directly.\nS:U - The impact remains within the local kernel/host security authority and does not cross a VM, IOMMU, or separate security-scope boundary.\nC:H - The bug causes an unbounded slab out-of-bounds read of iovec entries from kernel heap memory, and it is not strictly limited to a small fixed disclosure surface.\nI:N - The immediate primitive is an out-of-bounds read used for buffer accounting, with no demonstrated arbitrary kernel write or control-flow modification.\nA:H - The out-of-bounds read can trigger a KASAN/oops crash or an unbounded loop/page fault in kernel context, causing high availability impact."
}
]
}
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"providerMetadata": {
"dateUpdated": "2026-08-05T12:25:06.767Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
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"references": [
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"url": "https://git.kernel.org/stable/c/90ced24c500ad4e129e9e34b7e56fd7849e350b6"
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{
"url": "https://git.kernel.org/stable/c/c314b405dcc4d8b9041124f928f81715d6328bec"
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{
"url": "https://git.kernel.org/stable/c/1b655cd311344117d3052f6552cb20d9901c9d7c"
},
{
"url": "https://git.kernel.org/stable/c/b948f9d5d3057b01188e36664e7c7604d1c8ecb5"
}
],
"title": "io_uring/net: fix slab-out-of-bounds read in io_bundle_nbufs()",
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"cveMetadata": {
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"assignerShortName": "Linux",
"cveId": "CVE-2026-31774",
"datePublished": "2026-05-01T14:15:02.903Z",
"dateReserved": "2026-03-09T15:48:24.140Z",
"dateUpdated": "2026-08-05T12:25:06.767Z",
"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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