Vulnerability-Lookup

FKIE_CVE-2026-74653

Vulnerability from fkie_nvd - Published: 2026-08-22 16:16 - Updated: 2026-08-27 13:18

Severity

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
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/1423415471274abda87024967d7fe2206ceee0ea
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/3ce24bc4d115336218e59b7e286fd3a79f4fc4c6
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/7795e8abedc86438cae0454602cbf9038b94bf38
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/c321dc5172c8c66e21ffbeeb7a2ebb88ae6fd4c3

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "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": [
            {
              "lessThan": "c321dc5172c8c66e21ffbeeb7a2ebb88ae6fd4c3",
              "status": "affected",
              "version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
              "versionType": "git"
            },
            {
              "lessThan": "3ce24bc4d115336218e59b7e286fd3a79f4fc4c6",
              "status": "affected",
              "version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
              "versionType": "git"
            },
            {
              "lessThan": "7795e8abedc86438cae0454602cbf9038b94bf38",
              "status": "affected",
              "version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
              "versionType": "git"
            },
            {
              "lessThan": "1423415471274abda87024967d7fe2206ceee0ea",
              "status": "affected",
              "version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
              "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"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "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."
    }
  ],
  "id": "CVE-2026-74653",
  "lastModified": "2026-08-27T13:18:35.877",
  "metrics": {},
  "published": "2026-08-22T16:16:38.827",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1423415471274abda87024967d7fe2206ceee0ea"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3ce24bc4d115336218e59b7e286fd3a79f4fc4c6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7795e8abedc86438cae0454602cbf9038b94bf38"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c321dc5172c8c66e21ffbeeb7a2ebb88ae6fd4c3"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-74653 (GCVE-0-2026-74653)

Vulnerability from cvelistv5 – Published: 2026-08-22 15:32 – Updated: 2026-08-27 12:39

Title

serial: 8250_of: clear stuck empty-FIFO RX-timeout on LPC32xx

Summary

Severity

No CVSS data available.

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/c321dc5172c8c66e2…
https://git.kernel.org/stable/c/3ce24bc4d11533621…
https://git.kernel.org/stable/c/7795e8abedc86438c…
https://git.kernel.org/stable/c/1423415471274abda…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: e6e912c4964ce5976e508881207dfa96d5f856d7 , < c321dc5172c8c66e21ffbeeb7a2ebb88ae6fd4c3 (git) Affected: e6e912c4964ce5976e508881207dfa96d5f856d7 , < 3ce24bc4d115336218e59b7e286fd3a79f4fc4c6 (git) Affected: e6e912c4964ce5976e508881207dfa96d5f856d7 , < 7795e8abedc86438cae0454602cbf9038b94bf38 (git) Affected: e6e912c4964ce5976e508881207dfa96d5f856d7 , < 1423415471274abda87024967d7fe2206ceee0ea (git)
Linux	Linux	Affected: 2.6.36 Unaffected: 0 , < 2.6.36 (semver) Unaffected: 6.12.106 , ≤ 6.12.* (semver) Unaffected: 6.18.45 , ≤ 6.18.* (semver) Unaffected: 7.1.9 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "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": [
            {
              "lessThan": "c321dc5172c8c66e21ffbeeb7a2ebb88ae6fd4c3",
              "status": "affected",
              "version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
              "versionType": "git"
            },
            {
              "lessThan": "3ce24bc4d115336218e59b7e286fd3a79f4fc4c6",
              "status": "affected",
              "version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
              "versionType": "git"
            },
            {
              "lessThan": "7795e8abedc86438cae0454602cbf9038b94bf38",
              "status": "affected",
              "version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
              "versionType": "git"
            },
            {
              "lessThan": "1423415471274abda87024967d7fe2206ceee0ea",
              "status": "affected",
              "version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
              "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",
                  "versionStartIncluding": "2.6.36",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.9",
                  "versionStartIncluding": "2.6.36",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "2.6.36",
                  "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"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

FKIE_CVE-2026-74653

CVE-2026-74653 (GCVE-0-2026-74653)

Tags

Sightings

Nomenclature