CVE-2026-23472: Linux kernel · serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 4% 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:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 3 Apr 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 25.10linuxpkg:deb/ubuntu/linux?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=questingOther 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 is available in the Linux kernel. Users should update to a kernel version that includes the patch which makes uart_write_room() check xmit_buf and return 0 when NULL, consistent with uart_write(). No additional mitigation is required once the patch is applied.
Description
A vulnerability in the Linux kernel's serial core caused an infinite loop in the handle_tx() function when dealing with PORT_UNKNOWN serial ports. This occurred due to inconsistent behavior between uart_write_room() and uart_write() when the transmit buffer (xmit_buf) was NULL. The issue could cause system hangs in drivers relying on tty_write_room() to determine write capability. The vulnerability has been resolved by making uart_write_room() check xmit_buf and return 0 if NULL, aligning its behavior with uart_write().
References
- ubuntu.com/security/CVE-2026-23472 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23472 (opens in a new tab)
- git.kernel.org/linus/455ce986fa356ff43a43c0d363ba95fa152f21d5 (opens in a new tab)
- git.kernel.org/stable/c/455ce986fa356ff43a43c0d363ba95fa152f21d5 (opens in a new tab)
- git.kernel.org/stable/c/bc70f2b36cf474d5cc8ecbcaf57f3e326fdec67c (opens in a new tab)
- git.kernel.org/stable/c/efe85a557186b7fe915572ae93a8f3f78bfd9a22 (opens in a new tab)