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Review reviewHigh

CVE-2026-63883

Linux

In the Linux kernel, the following vulnerability has been resolved: serial: qcom_geni: fix kfifo underflow when flush precedes DMA completion IRQ When uart_flush_buffer() runs before the DMA completion IRQ is delivered, the following race can occur (all steps serialized by uart_port_lock): 1. DMA starts: tx_remaining = N, kfifo contains N bytes 2. DMA completes in hardware; IRQ is pending but not yet delivered 3. uart_flush_buffer() acquires the port lock and calls kfifo_reset(), making kfifo_len() = 0 while tx_remaining remains N 4. uart_flush_buffer() releases the port lock 5. DMA IRQ fir...

CVSS
7.3
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.07.20
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7.3

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: serial: qcom_geni: fix kfifo underflow when flush precedes DMA completion IRQ When uart_flush_buffer() runs before the DMA completion IRQ is delivered, the following race can occur (all steps serialized by uart_port_lock): 1. DMA starts: tx_remaining = N, kfifo contains N bytes 2. DMA completes in hardware; IRQ is pending but not yet delivered 3. uart_flush_buffer() acquires the port lock and calls kfifo_reset(), making kfifo_len() = 0 while tx_remaining remains N 4. uart_flush_buffer() releases the port lock 5. DMA IRQ fir...

Affected product and versions

Product
Linux
Affected versions
>= 2aaa43c7077833301c237684cd7bc9ae5e3dec95 < c91ea13375f70f6271a0183445e34e83b8f4d8f7, >= 2aaa43c7077833301c237684cd7bc9ae5e3dec95 < b1159dce10b38eb795e4c96cdc4d34b83cec81c5, >= 2aaa43c7077833301c237684cd7bc9ae5e3dec95 < 654f45a8569f3cd6ff20bd724a18e0cce65893ba, >= 2aaa43c7077833301c237684cd7bc9ae5e3dec95 < 0d2c41a8b00934ddf8a7c1b4cf72dffa1e629c46, >= 2aaa43c7077833301c237684cd7bc9ae5e3dec95 < 452d6fa37ae9b021f4f6d397dbae077f7296f6f4, >= 6.3
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L
CWE
Not available