CVE-2026-53306: tty: hvc_iucv: fix off-by-one in number of supported devices
In the Linux kernel, the following vulnerability has been resolved:
tty: hvciucv: fix off-by-one in number of supported devices
MAXHVCIUCVLINES == HVCALLOCTTYADAPTERS == 8. This is the number of entries in: static struct hvciucvprivate hvciucvtable[MAXHVCIUCVLINES];
Sometimes hvciucvtable[] is limited by: (a) if (num > hvciucvdevices) // for error detection or (b) for (i = 0; i < hvciucvdevices; i++) // in 2 places (so these 2 don't agree; second one appears to be correct to me.)
hvciucvdevices can be 0..8. This is a counter. (c) if (hvciucvdevices > MAXHVCIUCVLINES)
If hvciucvdevices == 8, (a) allows the code to access hvciucvtable[8]. Oops.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Linux kernelto a version that resolves this vulnerability.Fixed in MAX_HVC_IUCV_LINES == HVC_ALLOC_TTY_ADAPTERS == 8 - Upgrade
Upgrade
Linux kernelto a version that resolves this vulnerability.Patch tty: hvc_iucv: fix off-by-one in number of supported devices
Event History
Frequently Asked Questions
What is the severity of CVE-2026-53306?
CVE-2026-53306 has a risk score of 27, indicating moderate severity.
How do I fix CVE-2026-53306?
To fix CVE-2026-53306, update your Linux kernel to the latest patched version.
What does CVE-2026-53306 affect?
CVE-2026-53306 affects the tty subsystem in the Linux kernel.
What type of vulnerability is CVE-2026-53306?
CVE-2026-53306 is an off-by-one error in the number of supported devices.
When was CVE-2026-53306 published?
CVE-2026-53306 was published on June 26, 2026.