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NVD / CVE Program· CNA Linux

CVE-2026-53306: tty: hvc_iucv: fix off-by-one in number of supported devices

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.16% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 11207e42a332eb8bbcb9fe74df9edd2a807c5607, 3104a3f40feb107f77d7116ad9bf6c210ab7babf, 3d3b89e6ab93bdd0efd45828bda6b0e61cc46dff.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 11207e42a332eb8bbcb9fe74df9edd2a807c5607, 3104a3f40feb107f77d7116ad9bf6c210ab7babf, 3d3b89e6ab93bdd0efd45828bda6b0e61cc46dff or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Jun 26, 2026
Updated
Jul 6, 2026
EPSS
0.1% · 5th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel2.6.29 and later · before 5.10.258
  • linux linux kernel5.11 and later · before 5.15.209
  • linux linux kernel5.16 and later · before 6.1.175
  • linux linux kernel6.2 and later · before 6.6.141
  • linux linux kernel6.7 and later · before 6.12.91
  • linux linux kernel6.13 and later · before 6.18.33
  • linux linux kernel6.19 and later · before 7.0.10

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.29affected
    • 44a01d5ba8a4d543694461cd3e178cfa6b3f221b and later · before 3d3b89e6ab93bdd0efd45828bda6b0e61cc46dffaffected · git
    • 44a01d5ba8a4d543694461cd3e178cfa6b3f221b and later · before 484357dff256c816d9466bda35eb765685e4dc86affected · git
    • 44a01d5ba8a4d543694461cd3e178cfa6b3f221b and later · before 11207e42a332eb8bbcb9fe74df9edd2a807c5607affected · git
    • 44a01d5ba8a4d543694461cd3e178cfa6b3f221b and later · before fed8b8f33a46db0ee2efdb000f4f630c86ed8ca4affected · git
    • 44a01d5ba8a4d543694461cd3e178cfa6b3f221b and later · before a76511bc654819425d3b15e77b523d7f9d81f064affected · git
    • 44a01d5ba8a4d543694461cd3e178cfa6b3f221b and later · before 3104a3f40feb107f77d7116ad9bf6c210ab7babfaffected · git
    • 44a01d5ba8a4d543694461cd3e178cfa6b3f221b and later · before f1dc8e72de9aabe5d96767a4e97219ac26b79fe5affected · git
    • 44a01d5ba8a4d543694461cd3e178cfa6b3f221b and later · before f2a880e802ad12d1e38039d1334fb1475d0f5241affected · git
    • before 2.6.29not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.176-16.1.176-1
Debian:13linuxbefore 6.12.94-16.12.94-1
Debian:14linuxbefore 7.0.10-17.0.10-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-53304Jun 26, 2026 · scsi: sg: Resolve soft lockup issue when opening /dev/sgX
    22Monitor
  • ← EarlierCVE-2026-53305Jun 26, 2026 · usb: typec: ps883x: Fix Oops at unbind
    22Monitor
  • Later →CVE-2026-53307Jun 26, 2026 · pinctrl: pinconf-generic: Fully validate 'pinmux' property
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux11207e42a332eb8bbcb9fe74df9edd2a807c5607Vendor (CNA)
Linux Linux3104a3f40feb107f77d7116ad9bf6c210ab7babfVendor (CNA)
Linux Linux3d3b89e6ab93bdd0efd45828bda6b0e61cc46dffVendor (CNA)
Linux Linux484357dff256c816d9466bda35eb765685e4dc86Vendor (CNA)
Linux Linuxa76511bc654819425d3b15e77b523d7f9d81f064Vendor (CNA)
Linux Linuxf1dc8e72de9aabe5d96767a4e97219ac26b79fe5Vendor (CNA)
Linux Linuxf2a880e802ad12d1e38039d1334fb1475d0f5241Vendor (CNA)
Linux Linuxfed8b8f33a46db0ee2efdb000f4f630c86ed8ca4Vendor (CNA)
debian:linux6.1.176-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-533090 days apartocfs2/dlm: fix off-by-one in dlm_match_regions() region comparison
    39Monitor
  • CVE-2026-530882 days apartnet: bcmgenet: fix off-by-one in bcmgenet_put_txcb
    39Monitor
  • CVE-2026-6404723 days apartnet: tls: fix off-by-one in sg_chain entry count for wrapped sk_msg ring
    39Monitor
  • CVE-2026-530362 days apartbpf, arm64: Fix off-by-one in check_imm signed range check
    31Monitor
  • CVE-2026-5290717 days apartmedia: rockchip: rkcif: fix off by one bugs
    31Monitor
  • CVE-2024-57990485 days apartwifi: mt76: mt7925: fix off by one in mt7925_load_clc()
    31Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-193 · Off-by-one Error

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records