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NVD / CVE Program· CNA Linux

CVE-2026-68453: s390/zcrypt: Fix buffer over-read in cca_cipher2protkey

Noroxi assessment

Priority: Monitor (action score 28/100)

  • 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 1adfec7be6f34c1073c9cf15040bc4e3fdc6dc51, 353e442d18084b24fb3ede4e5adfca26b25f0e89, 36b230835b8a008266aad22168ca52afacc8a58d.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 1adfec7be6f34c1073c9cf15040bc4e3fdc6dc51, 353e442d18084b24fb3ede4e5adfca26b25f0e89, 36b230835b8a008266aad22168ca52afacc8a58d 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: s390/zcrypt: Fix buffer over-read in cca_cipher2protkey Add validation of both the actual key buffer size and token length fields in all the cca_check_sec*token() functions. Additionally check in cca_gencipherkey() for possible underflow with returned key size. The CCA token structures contain user-controlled len fields that were used in operations without proper validation against both the actual buffer size and minimum token structure size. An attacker could set this field larger than the actual buffer size, leading to reading beyond buffer boundaries. This may result in a kernel crash or exposure of memory via sending this as part of a request down to the crypto card. Also an attacker could have used a very small len value and thus enforce a buffer under-run which may produce similar effects as a over-read. So now a key must - key buf length must be at least sizeof the token struct - the key len field inside the token must fit into the range of sizeof key token struct ... key buf length

HighCVSS 7.1 · v3.1—No exploit Fix available
Published
Aug 13, 2026
Updated
Oct 30, 2026
EPSS
0.1% · 5th percentile

Report tools

JSON

Action score

28

Monitor

Low priority for now.

CVSS
28 / 40 · 7.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.1
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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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.

—

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

    • 5.4affected
    • 4bc123b18ce6ae6c42c69d0456b5acbd2f7bc8bd and later · before 1adfec7be6f34c1073c9cf15040bc4e3fdc6dc51affected · git
    • 4bc123b18ce6ae6c42c69d0456b5acbd2f7bc8bd and later · before d0951ed366710a1a303b7cb2f8eb3d866cd68fc6affected · git
    • 4bc123b18ce6ae6c42c69d0456b5acbd2f7bc8bd and later · before 353e442d18084b24fb3ede4e5adfca26b25f0e89affected · git
    • 4bc123b18ce6ae6c42c69d0456b5acbd2f7bc8bd and later · before a57fd7fcdb63e2d5ceac78bbe825ec986062a9daaffected · git
    • 4bc123b18ce6ae6c42c69d0456b5acbd2f7bc8bd and later · before 3b2abee2a678607ae27975bc6833785c2002df43affected · git
    • 4bc123b18ce6ae6c42c69d0456b5acbd2f7bc8bd and later · before 36b230835b8a008266aad22168ca52afacc8a58daffected · git
    • before 5.4not affected · semver
    • 6.1.191 and later · up to and including 6.1.*not affected · semver
    • 6.6.160 and later · up to and including 6.6.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:14linuxbefore 7.1.8-17.1.8-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-68451Aug 13, 2026 · s390/zcrypt: Validate length for CCA ECC private key requests
    31Monitor
  • ← EarlierCVE-2026-68452Aug 13, 2026 · s390/zcrypt: Validate length for CCA AES cipher key requests
    31Monitor
  • Later →CVE-2026-68454Aug 13, 2026 · KVM: s390: pci: Fix handling of AIF enable without AISB
    35Monitor

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 Linux1adfec7be6f34c1073c9cf15040bc4e3fdc6dc51Vendor (CNA)
Linux Linux353e442d18084b24fb3ede4e5adfca26b25f0e89Vendor (CNA)
Linux Linux36b230835b8a008266aad22168ca52afacc8a58dVendor (CNA)
Linux Linux3b2abee2a678607ae27975bc6833785c2002df43Vendor (CNA)
Linux Linuxa57fd7fcdb63e2d5ceac78bbe825ec986062a9daVendor (CNA)
Linux Linuxd0951ed366710a1a303b7cb2f8eb3d866cd68fc6Vendor (CNA)
debian:linux7.1.8-1 · Debian:14Package 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-2026-720842 days apartscsi: target: Bound PR-OUT TransportID parsing to the received buffer
    39Monitor
  • CVE-2026-681603 days apartceph: fix pre-auth out-of-bounds read on snaptrace in ceph_handle_caps()
    39Monitor
  • CVE-2026-683883 days apartsmb/client: handle overlapping allocated ranges in fallocate
    39Monitor
  • CVE-2026-680825 days apartlibceph: fix two unsafe bare decodes in decode_lockers()
    39Monitor
  • CVE-2026-683433 days apartsmb: client: validate DFS referral PathConsumed
    36Monitor
  • CVE-2026-6455117 days apartsctp: validate STALE_COOKIE cause length before reading staleness
    36Monitor

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
high · data can be read
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
High
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

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

nvd-secondary

Attack context

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

ATT&CK techniques

—

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

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

References

Show all references (5 more)

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

All records