CVE-2026-74655: Linux kernel · serial: qcom-geni: fix TX DMA buffer flush
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 8.8 High.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 22 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix for this vulnerability has been implemented in the Linux kernel. Users should update to the patched kernel version that includes the fix for CVE-2026-74655. Since this is a kernel-level issue, applying the official kernel update from the Linux distribution vendor is the recommended remediation. No additional mitigations are indicated by the vendor advisory.
Description
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.
References
- nvd.nist.gov/vuln/detail/CVE-2026-74655 (opens in a new tab)
- git.kernel.org/stable/c/1c31e2377f4c1bb110ca7f6e597b2253a7440c37 (opens in a new tab)
- git.kernel.org/stable/c/313ae287442e5e8d3f7b53b73f37d384bda072d0 (opens in a new tab)
- git.kernel.org/stable/c/b1801c0d40f62778b613334de5840aba10a564d5 (opens in a new tab)
- git.kernel.org/stable/c/e3c04834ae1ab5e9cfbe8ac54ec734aa4774249d (opens in a new tab)
- ubuntu.com/security/CVE-2026-74655 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-74655 (opens in a new tab)
- git.kernel.org/stable/c/1606abb7ce8c0cfef98c7e556b83c14e5d73c1bf (opens in a new tab)