CVE-2026-74653 (GCVE-0-2026-74653)
Vulnerability from cvelistv5
Published
2026-08-22 15:32
Modified
2026-08-27 12:39
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
serial: 8250_of: clear stuck empty-FIFO RX-timeout on LPC32xx
The NXP LPC32xx UART (PORT_LPC3220) can latch an RX character-timeout
interrupt while the RX FIFO is empty: IIR reports UART_IIR_RX_TIMEOUT
(0x0c) but LSR.DR is clear. A character timeout is only cleared by
reading RHR, but serial8250_rx_chars() reads RHR only when LSR.DR is
set, so nothing ever clears the condition. The interrupt is
level-triggered and re-fires immediately, so on a single-core ARM926
the resulting interrupt storm livelocks the CPU.
It is reproducible when userspace repeatedly opens the front-panel port
(ttyS1): serial8250_do_set_termios() re-enables interrupts on unlock and
the handler then spins forever with iir=0xcc lsr=0x60 ier=0x05, tripping
the soft-lockup detector in serial8250_handle_irq_locked().
LPC32xx has no dedicated 8250 glue driver, it's driven by the generic
8250_of. Add a hardware specific handle_irq for PORT_LPC3220, wired up
in of_platform_serial_setup() the same way fsl8250_handle_irq is
installed. The handler follows dw8250_handle_irq(): on an RX timeout
with an empty FIFO (LSR.DR and LSR.BI clear) it does one throwaway RHR
read to clear the condition, then calls serial8250_handle_irq_locked().
No real received data is ever discarded, and it is a no-op on healthy
UARTs which never report a timeout with DR clear.
This is the same class of bug already worked around in other 8250 drivers;
see commit 424d79183af0 ("serial: 8250_dw: Avoid "too much work" from bogus rx timeout interrupt")
which reports the identical iir=0xcc/lsr=0x60. See also
UART_RX_TIMEOUT_QUIRK in 8250_omap, and the note in 8250_bcm7271.
References
| URL | Tags | |
|---|---|---|
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"drivers/tty/serial/8250/8250_of.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
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"version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
"versionType": "git"
},
{
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"version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
"versionType": "git"
},
{
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"status": "affected",
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"versionType": "git"
},
{
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"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"drivers/tty/serial/8250/8250_of.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.36"
},
{
"lessThan": "2.6.36",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.106",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.45",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.9",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.106",
"versionStartIncluding": "2.6.36",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.45",
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"vulnerable": true
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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\nserial: 8250_of: clear stuck empty-FIFO RX-timeout on LPC32xx\n\nThe NXP LPC32xx UART (PORT_LPC3220) can latch an RX character-timeout\ninterrupt while the RX FIFO is empty: IIR reports UART_IIR_RX_TIMEOUT\n(0x0c) but LSR.DR is clear. A character timeout is only cleared by\nreading RHR, but serial8250_rx_chars() reads RHR only when LSR.DR is\nset, so nothing ever clears the condition. The interrupt is\nlevel-triggered and re-fires immediately, so on a single-core ARM926\nthe resulting interrupt storm livelocks the CPU.\n\nIt is reproducible when userspace repeatedly opens the front-panel port\n(ttyS1): serial8250_do_set_termios() re-enables interrupts on unlock and\nthe handler then spins forever with iir=0xcc lsr=0x60 ier=0x05, tripping\nthe soft-lockup detector in serial8250_handle_irq_locked().\n\nLPC32xx has no dedicated 8250 glue driver, it\u0027s driven by the generic\n8250_of. Add a hardware specific handle_irq for PORT_LPC3220, wired up\nin of_platform_serial_setup() the same way fsl8250_handle_irq is\ninstalled. The handler follows dw8250_handle_irq(): on an RX timeout\nwith an empty FIFO (LSR.DR and LSR.BI clear) it does one throwaway RHR\nread to clear the condition, then calls serial8250_handle_irq_locked().\nNo real received data is ever discarded, and it is a no-op on healthy\nUARTs which never report a timeout with DR clear.\n\nThis is the same class of bug already worked around in other 8250 drivers;\nsee commit 424d79183af0 (\"serial: 8250_dw: Avoid \"too much work\" from bogus rx timeout interrupt\")\nwhich reports the identical iir=0xcc/lsr=0x60. See also\nUART_RX_TIMEOUT_QUIRK in 8250_omap, and the note in 8250_bcm7271."
}
],
"providerMetadata": {
"dateUpdated": "2026-08-27T12:39:55.086Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/c321dc5172c8c66e21ffbeeb7a2ebb88ae6fd4c3"
},
{
"url": "https://git.kernel.org/stable/c/3ce24bc4d115336218e59b7e286fd3a79f4fc4c6"
},
{
"url": "https://git.kernel.org/stable/c/7795e8abedc86438cae0454602cbf9038b94bf38"
},
{
"url": "https://git.kernel.org/stable/c/1423415471274abda87024967d7fe2206ceee0ea"
}
],
"title": "serial: 8250_of: clear stuck empty-FIFO RX-timeout on LPC32xx",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74653",
"datePublished": "2026-08-22T15:32:28.521Z",
"dateReserved": "2026-08-15T05:44:03.923Z",
"dateUpdated": "2026-08-27T12:39:55.086Z",
"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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