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Fencer Vulns
high 8.8

CVE-2026-74655 json

serial: qcom-geni: fix TX DMA buffer flush

published 2026-08-22 2 mo ago modified 2026-10-14 26 d ago also EUVD-2026-64592

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

serial: qcom-geni: fix TX DMA buffer flush

When transmit flushing a qcom-geni UART during an ongoing TX DMA, the UART gets stuck infinitely repeating corrupted TX DMA frames.

The DMA-mode uart_ops does not provide a flush_buffer callback, so an in-flight transfer can complete after serial core has reset the transmit kfifo, underflowing its length and resubmitting page-sized transfers indefinitely. Add one that stops the transfer and clears tx_remaining and tx_queued.

The stop path was also broken: it unmapped the buffer while the serial engine could still read it, and never reset the TX DMA state machine. Cancel the main sequencer command first, then reset the state machine and wait for it before unmapping. Drop the early return so a pending mapping is also cleaned up when the main command is inactive.

The bug can be triggered from userspace with a large write immediately followed by TCOFLUSH. A following tcdrain will hang forever. The bug was reproduced and this fix was validated on Arduino Uno Q (QRB2210) using /dev/ttyHS1.

Patch / fix

  • Linux Linux 6.6.154, 6.12.104, 6.18.45, 7.1.9, 7.2
  • linux Debian 13 6.12.105-1
  • linux Debian 14 7.1.9-1
  • linux-6.12 Debian 12 6.12.107-1~deb12u1

debian advisories DEBIAN-CVE-2026-74655

  • linux Ubuntu 26.04 LTS 7.0.0-42.42
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1016.17
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1016.18
  • linux-ibm Ubuntu 26.04 LTS 7.0.0-1017.17
  • linux-riscv Ubuntu 26.04 LTS 7.0.0-42.42.1
  • linux-oracle Ubuntu 26.04 LTS 7.0.0-1015.16
  • linux-hwe-7.0 Ubuntu 24.04 LTS 7.0.0-42.42~24.04.1
  • linux-oem-7.0 Ubuntu 26.04 LTS 7.0.0-1017.17

ubuntu advisories UBUNTU-CVE-2026-74655

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-source Linux Micro 6.0 6.4.0-159998.55.1
  • kernel-default Linux Micro 6.0 6.4.0-159998.55.1
  • kernel-kvmsmall Linux Micro 6.0 6.4.0-159998.55.1
  • kernel-default-base Linux Micro 6.0 6.4.0-159998.55.1.159998.21.42
  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.90.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.90.1
  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.90.1
  • kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.90.1

suse advisories SUSE-SU-2026:24550-1SUSE-SU-2026:5091-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-74655 updated cvss 5.5

kernel: serial: qcom-geni: fix TX DMA buffer flush

  • Red Hat Enterprise Linux 10 kernel
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.