CVE-2026-98773
In the Linux kernel, the following vulnerability has been resolved:
USB: cdc-acm: skip URB restart in port_shutdown if disconnected
acm_port_shutdown() is called from the tty-port machinery whenever the last user closes the port. acm_disconnect() sets acm->disconnected and calls tty_port_tty_vhangup(), which eventually triggers port_shutdown(). At that point acm_disconnect() has already called acm_poison_urbs() and is about to free the control and read URBs.
However, acm_port_shutdown() unconditionally calls acm_unpoison_urbs() and, when the ALWAYS_POLL_CTRL quirk is set, immediately re-submits the ctrlurb and all read URBs.
Read full descriptionShow less
If the concurrent acm_disconnect() then frees those URBs and their DMA buffers while they are in-flight, the result is a use-after-free in acm_ctrl_irq() or acm_read_bulk_callback() accessing the freed DMA memory.
Fix by checking acm->disconnected after draining the delayed anchor and returning early: if we are in a disconnect path the URBs must remain poisoned and must not be resubmitted.
The early return is placed after the delayed-anchor drain loop because that loop only cancels write-side accounting (wb->use = false and autopm counter) and does not touch the hardware path.
CVSS
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
- 0.17 %
- Percentile among all scored CVEs
- 6
- 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
Show 4 references
Raw JSON (NVD)
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{
"id": "CVE-2026-98773",
"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": "603d5a7110832e10165d21f9a1486399457177de",
"lessThan": "9742905d9ed5bf23ebe4c100dec80b6bc50fb522",
"versionType": "git"
},
{
"status": "affected",
"version": "5d29d7ff8679e5a525f22da467ba33c042e8029b",
"lessThan": "a0ed07b5bbb2d8fcef86810453216070691816e7",
"versionType": "git"
},
{
"status": "affected",
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{
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{
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{
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"version": "8fb82e3555a7d56a05d8ef0edee9859f889c0860",
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{
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{
"status": "affected",
"version": "f77f10bc76c2da86b4248269472f6d971e37828b",
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{
"status": "affected",
"version": "6.12.83",
"lessThan": "6.12.113",
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{
"status": "affected",
"version": "6.18.24",
"lessThan": "6.18.56",
"versionType": "semver"
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{
"status": "affected",
"version": "6.1.175",
"lessThan": "6.2",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.6.136",
"lessThan": "6.7",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.19.14",
"lessThan": "6.20",
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},
{
"status": "affected",
"version": "7.0.1",
"lessThan": "7.1",
"versionType": "semver"
}
],
"programFiles": [
"drivers/usb/class/cdc-acm.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "7.1"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "7.1",
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{
"status": "unaffected",
"version": "6.12.113",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.56",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.10",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/usb/class/cdc-acm.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-10-18T16:17:31.223",
"references": [
{
"url": "https://git.kernel.org/stable/c/420ca35af891d33522cc08504768ccd60a4c450a",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/9742905d9ed5bf23ebe4c100dec80b6bc50fb522",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/a0ed07b5bbb2d8fcef86810453216070691816e7",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/dc614d6bc991740d41d5a99ac7765c4b675dda88",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nUSB: cdc-acm: skip URB restart in port_shutdown if disconnected\n\nacm_port_shutdown() is called from the tty-port machinery whenever the\nlast user closes the port. acm_disconnect() sets acm->disconnected and\ncalls tty_port_tty_vhangup(), which eventually triggers port_shutdown().\nAt that point acm_disconnect() has already called acm_poison_urbs() and\nis about to free the control and read URBs.\n\nHowever, acm_port_shutdown() unconditionally calls acm_unpoison_urbs()\nand, when the ALWAYS_POLL_CTRL quirk is set, immediately re-submits the\nctrlurb and all read URBs. If the concurrent acm_disconnect() then\nfrees those URBs and their DMA buffers while they are in-flight, the\nresult is a use-after-free in acm_ctrl_irq() or acm_read_bulk_callback()\naccessing the freed DMA memory.\n\nFix by checking acm->disconnected after draining the delayed anchor and\nreturning early: if we are in a disconnect path the URBs must remain\npoisoned and must not be resubmitted.\n\nThe early return is placed after the delayed-anchor drain loop because\nthat loop only cancels write-side accounting (wb->use = false and\nautopm counter) and does not touch the hardware path."
}
],
"lastModified": "2026-10-19T10:19:41.400",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}