CVE-2026-10642: The Zephyr PL011 UART driver (drivers/serial/uart_pl011.c) contains an unbounded software loop in pl011_irq_tx

Q: How do I fix CVE-2026-10642?

zephyr: upgrade to 4.5.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-10642 being exploited?

CVE-2026-10642 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-10642 affect?

CVE-2026-10642 affects zephyr. Severity is medium (CVSS 4.6). The Zephyr PL011 UART driver (drivers/serial/uart_pl011.c) contains an unbounded software loop in pl011_irq_tx_enable() that repeatedly invokes the interrupt-driven application callback while the TX interrupt mask bit (PL011_IMSC_TXIM) is s

Q: How urgent is CVE-2026-10642?

Priority 25/100. Public exploit reference

Routine

MEDIUM 4.6UPGRADE

CVE-2026-10642 is a medium-severity flaw (CVSS 4.6) affecting zephyr. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The Zephyr PL011 UART driver (drivers/serial/uart_pl011.c) contains an unbounded software loop in pl011_irq_tx_enable() that repeatedly invokes the interrupt-driven application callback while the TX interrupt mask bit (PL011_IMSC_TXIM) is set, to work around the controller's level-transition TX-interrupt behavior. When CTS hardware flow control is enabled (devicetree hw-flow-control or runtime UART_CFG_FLOW_CTRL_RTS_CTS) and the wired serial pee

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	4.6 (Medium)
Attack vector	Physical
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 85%)
CISA exploited list	No
Weakness	CWE-835
Published	2026-06-24
Last modified	2026-10-25

Publisher (CNA): Zephyr Project · Vendor: zephyrproject

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-24 22:16 UTCPublished CVE record published
2026-10-25 23:10 UTCUpdated Record last modified

zephyrproject zephyr UPGRADE

Affected: >= 4.1.0 and < 4.5.0

Fixed in: 4.5.0

Safe to downgrade to: a release before 4.1.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-10642?

zephyr: upgrade to 4.5.0. Exact commands for each OS are on this page.

Is CVE-2026-10642 being exploited?

CVE-2026-10642 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-10642 affect?

CVE-2026-10642 affects zephyr. Severity is medium (CVSS 4.6). The Zephyr PL011 UART driver (drivers/serial/uart_pl011.c) contains an unbounded software loop in pl011_irq_tx_enable() that repeatedly invokes the interrupt-driven application callback while the TX interrupt mask bit (PL011_IMSC_TXIM) is s

How urgent is CVE-2026-10642?

Priority 25/100. Public exploit reference

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References

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