VulnerabilityPublished 3 Apr 2026Updated 21 Oct 2026

CVE-2026-23472: Linux kernel · serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in efe85a557186b7fe915572ae93a8f3f78bfd9a22 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 12:55 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

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.
Patch: Available – fixed in efe85a557186b7fe915572ae93a8f3f78bfd9a22, d45cfa70bf0159afb31cb03d2d16ec5a5053460c, c9e845014723d552944cec4e146ec7b841cda34d +2

Exploitation 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.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < efe85a557186b7fe915572ae93a8f3f78bfd9a22	Fixed in efe85a557186b7fe915572ae93a8f3f78bfd9a22
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < d45cfa70bf0159afb31cb03d2d16ec5a5053460c	Fixed in d45cfa70bf0159afb31cb03d2d16ec5a5053460c
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < c9e845014723d552944cec4e146ec7b841cda34d	Fixed in c9e845014723d552944cec4e146ec7b841cda34d
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < bc70f2b36cf474d5cc8ecbcaf57f3e326fdec67c	Fixed in bc70f2b36cf474d5cc8ecbcaf57f3e326fdec67c
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 455ce986fa356ff43a43c0d363ba95fa152f21d5	Fixed in 455ce986fa356ff43a43c0d363ba95fa152f21d5
LinuxLinux	Affected =2.6.12	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWN uart_write_room() and uart_write() behave inconsistently when xmit_buf is NULL (which happens for PORT_UNKNOWN ports that were never properly initialized): - uart_write_room() returns kfifo_avail() which can be > 0 - uart_write() checks xmit_buf and returns 0 if NULL This inconsistency causes an infinite loop in drivers that rely on tty_write_room() to determine if they can write: while (tty_write_room(tty) > 0) { written = tty->ops->write(...); // written is always 0, loop never exits } For example, caif_serial's handle_tx() enters an infinite loop when used with PORT_UNKNOWN serial ports, causing system hangs. Fix by making uart_write_room() also check xmit_buf and return 0 if it's NULL, consistent with uart_write(). Reproducer: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13

References

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