CVE-2026-98584
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:
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.
Read full descriptionShow less
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.
Technical details traces, logs and code from the original report
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 uninitializedCVSS
NVD hasn't assigned a CVSS score to this CVE (common since the April 2026 policy change).
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days
- 0.20 %
- Percentile among all scored CVEs
- 9
- Score date
- 10/20/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Affected technologies (1)
⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.
References
Raw JSON (NVD)
Show
{
"id": "CVE-2026-98584",
"cveTags": [],
"metrics": {},
"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": "b04202d6065cba5dfd51fb9866400b25573eac67",
"lessThan": "9923e1c537f91f3530b52d4efce85f3d9c131bf8",
"versionType": "git"
},
{
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"lessThan": "0b160417826d22f24fc31a5b9cfae3b14aa70f76",
"versionType": "git"
},
{
"status": "affected",
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"lessThan": "9c572a83037a7dcd653ba3a9cc468c16b857d0c9",
"versionType": "git"
}
],
"programFiles": [
"net/sched/em_text.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.17"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.17",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.18.55",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.9",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/sched/em_text.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-10-18T16:17:10.983",
"references": [
{
"url": "https://git.kernel.org/stable/c/0b160417826d22f24fc31a5b9cfae3b14aa70f76",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/9923e1c537f91f3530b52d4efce85f3d9c131bf8",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/9c572a83037a7dcd653ba3a9cc468c16b857d0c9",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"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."
}
],
"lastModified": "2026-10-19T10:19:19.270",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}