Is CVE-2026-53306 in the CISA KEV catalog?

No. CVE-2026-53306 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-53306?

CVE-2026-53306 has a CVSS v3 base score of 7.1 (Important).

What is the EPSS score for CVE-2026-53306?

CVE-2026-53306 has an EPSS score of 0.18% (7th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-53306?

Upgrade linux on debian 12 to 6.1.176-1 or later.

CVE & CISA-KEV Catalog

CVE-2026-53306

HIGH

7.1

CVSS v3

NVD

Description

In the Linux kernel, the following vulnerability has been resolved: tty: hvc_iucv: fix off-by-one in number of supported devices MAX_HVC_IUCV_LINES == HVC_ALLOC_TTY_ADAPTERS == 8. This is the number of entries in: static struct hvc_iucv_private *hvc_iucv_table[MAX_HVC_IUCV_LINES]; Sometimes hvc_iucv_table[] is limited by: (a) if (num > hvc_iucv_devices) // for error detection or (b) for (i = 0; i < hvc_iucv_devices; i++) // in 2 places (so these 2 don't agree; second one appears to be correct to me.) hvc_iucv_devices can be 0..8. This is a counter. (c) if (hvc_iucv_devices > MAX_HVC_IUCV_LINES) If hvc_iucv_devices == 8, (a) allows the code to access hvc_iucv_table[8]. Oops.

How to fix

Remediation Available

linuxDebian

Fixed in:6.1.176-1CVE-2026-53306

Fixed in:6.12.94-1CVE-2026-53306

Fixed in:7.0.10-1CVE-2026-53306

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Exploit Intelligence

0.18%probability of exploitation in 30 days

7thpercentile

Low risk: more likely to be exploited than 7% of all known CVEs.

References

Other references8

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-30.