CVE-2026-53306

Local kernel crash via hvc_iucv off-by-one

Published Jun 26, 2026 · Updated Jun 26, 2026

Out-of-bounds access in affected Linux kernels allows local users to crash s390 z/VM guests through the hvc_iucv console driver. The hvc_iucv_get_private function treats the device count as a valid index, so a count of eight permits reading hvc_iucv_table[8] beyond the eight-entry array. Reachability requires a Linux s390 guest using the z/VM IUCV console facility with eight terminal devices; the reported consequence is service interruption, not data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds access in affected Linux kernels allows local users to crash s390 z/VM guests through the hvc_iucv console driver. The hvc_iucv_get_private function treats the device count as a valid index, so a count of eight permits reading hvc_iucv_table[8] beyond the eight-entry array. Reachability requires a Linux s390 guest using the z/VM IUCV console facility with eight terminal devices; the reported consequence is service interruption, not data disclosure or modification.

The record

CVE
CVE-2026-53306
Published
Jun 26, 2026
Updated
Jun 26, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-193, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.6.29
  2. Affected versionversion=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <11207e42a332eb8bbcb9fe74df9edd2a807c5607
  3. Affected versionversion=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <3104a3f40feb107f77d7116ad9bf6c210ab7babf
  4. Affected versionversion=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <3d3b89e6ab93bdd0efd45828bda6b0e61cc46dff
  5. Affected versionversion=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <484357dff256c816d9466bda35eb765685e4dc86
  6. Affected versionversion=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <a76511bc654819425d3b15e77b523d7f9d81f064
  7. Affected versionversion=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <f1dc8e72de9aabe5d96767a4e97219ac26b79fe5
  8. Affected versionversion=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <f2a880e802ad12d1e38039d1334fb1475d0f5241
  9. Affected versionversion=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <fed8b8f33a46db0ee2efdb000f4f630c86ed8ca4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=2.6.29; version=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <11207e42a332eb8bbcb9fe74df9edd2a807c5607; version=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <3104a3f40feb107f77d7116ad9bf6c210ab7babf; version=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <3d3b89e6ab93bdd0efd45828bda6b0e61cc46dff; version=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <484357dff256c816d9466bda35eb765685e4dc86; version=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <a76511bc654819425d3b15e77b523d7f9d81f064; version=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <f1dc8e72de9aabe5d96767a4e97219ac26b79fe5; version=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <f2a880e802ad12d1e38039d1334fb1475d0f5241; version=44a01d5ba8a4d543694461cd3e178cfa6b3f221b <fed8b8f33a46db0ee2efdb000f4f630c86ed8ca4

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-193Off-by-one Error
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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