CVE-2026-98584 (GCVE-0-2026-98584)
Vulnerability from cvelistv5
Published
2026-10-18 15:18
Modified
2026-10-19 09:22
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/sched: fix potential stack infoleak in em_text_dump()
em_text_dump() allocates struct tcf_em_text on the stack without zeroing
it. strscpy() writes the algorithm name and a NUL terminator into
conf.algo[], leaving the remaining bytes uninitialised. nla_put_nohdr()
then copies the full struct to the netlink response.
KMSAN on Linux 7.2-rc6 reports two kernel-infoleak splats from this path,
one triggered via "tc filter show" and one via a raw RTM_GETTFILTER dump:
BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x1c9/0x2620
nla_put_nohdr+0x83/0x130
em_text_dump+0x291/0x550
Local variable conf created at: em_text_dump+0x5d/0x550
Bytes 168-179 of 199 are uninitialized
I am not certain whether this constitutes a real security problem in
practice: the test was conducted in a controlled KMSAN environment and
the leaked stack bytes may or may not carry sensitive data on actual
production kernels. I am reporting it because KMSAN flagged it as a
kernel-infoleak and the fix is straightforward. I can provide a
userspace reproducer on request.
The original code used strncpy() which zero-pads to the destination size.
Commit b04202d6065c ("net/sched: replace strncpy with strscpy") replaced
it with strscpy(), which does not pad, creating this condition.
Zero-initialising the struct closes it.
References
Impacted products
{
"containers": {
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"product": "Linux",
"programFiles": [
"net/sched/em_text.c"
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"versions": [
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{
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"cpeApplicability": [
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"nodes": [
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"descriptions": [
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"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fix potential stack infoleak in em_text_dump()\n\nem_text_dump() allocates struct tcf_em_text on the stack without zeroing\nit. strscpy() writes the algorithm name and a NUL terminator into\nconf.algo[], leaving the remaining bytes uninitialised. nla_put_nohdr()\nthen copies the full struct to the netlink response.\n\nKMSAN on Linux 7.2-rc6 reports two kernel-infoleak splats from this path,\none triggered via \"tc filter show\" and one via a raw RTM_GETTFILTER dump:\n\n BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x1c9/0x2620\n nla_put_nohdr+0x83/0x130\n em_text_dump+0x291/0x550\n Local variable conf created at: em_text_dump+0x5d/0x550\n Bytes 168-179 of 199 are uninitialized\n\nI am not certain whether this constitutes a real security problem in\npractice: the test was conducted in a controlled KMSAN environment and\nthe leaked stack bytes may or may not carry sensitive data on actual\nproduction kernels. I am reporting it because KMSAN flagged it as a\nkernel-infoleak and the fix is straightforward. I can provide a\nuserspace reproducer on request.\n\nThe original code used strncpy() which zero-pads to the destination size.\nCommit b04202d6065c (\"net/sched: replace strncpy with strscpy\") replaced\nit with strscpy(), which does not pad, creating this condition.\nZero-initialising the struct closes it."
}
],
"providerMetadata": {
"dateUpdated": "2026-10-19T09:22:09.980Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"references": [
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"url": "https://git.kernel.org/stable/c/9923e1c537f91f3530b52d4efce85f3d9c131bf8"
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{
"url": "https://git.kernel.org/stable/c/0b160417826d22f24fc31a5b9cfae3b14aa70f76"
},
{
"url": "https://git.kernel.org/stable/c/9c572a83037a7dcd653ba3a9cc468c16b857d0c9"
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],
"title": "net/sched: fix potential stack infoleak in em_text_dump()",
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"cveId": "CVE-2026-98584",
"datePublished": "2026-10-18T15:18:57.204Z",
"dateReserved": "2026-09-25T10:25:14.358Z",
"dateUpdated": "2026-10-19T09:22:09.980Z",
"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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