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CVE Record

CVE-2026-43304: libceph: define and enforce CEPH_MAX_KEY_LEN

In the Linux kernel, the following vulnerability has been resolved: libceph: define and enforce CEPH_MAX_KEY_LEN When decoding the key, verify that the key material would fit into a fixed-size buffer in process_auth_done() and generally has a sane length. The new CEPH_MAX_KEY_LEN check replaces the existing check for a key with no key material which is a) not universal since CEPH_CRYPTO_NONE has to be excluded and b) doesn't provide much value since a smaller than needed key is just as invalid as no key -- this has to be handled elsewhere anyway.

CriticalCVSS 9.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

CVE-2026-43304 is a Linux kernel libceph flaw in how authentication key material is decoded. The kernel fix adds a maximum key length check before copying into a fixed-size buffer. The published CVSS is 9.8, so organizations using affected Linux kernels with libceph should treat this as urgent.

Executive priority

High priority for environments using Ceph-related Linux kernel functionality. The score is critical and the flaw is in kernel code, but evidence of active exploitation is not provided. Patch through normal emergency kernel update processes after testing.

Technical view

In process_auth_done(), libceph did not verify that decoded key material fit a fixed-size buffer or had a sane length. The fix defines and enforces CEPH_MAX_KEY_LEN. CVSS indicates network attack vector, low complexity, no privileges, no user interaction, and high confidentiality, integrity, and availability impact.

Likely exposure

Exposure is most relevant to Linux systems using libceph authentication, such as kernel Ceph-related functionality. The CVE record lists Linux as affected and provides stable kernel fix commits. CPEs and detailed distribution package mappings are not provided in the source bundle.

Exploitation context

The CVSS vector suggests remote, unauthenticated exploitability under the vulnerable code path. The provided sources do not show CISA KEV listing or confirmed active exploitation. Operational prerequisites are not fully described in the public CVE text.

Researcher notes

No CWE is assigned in the CVE data. The affected-version data lacks CPEs and distro mappings. Analysis should focus on the referenced kernel stable commits and whether downstream kernels backported the CEPH_MAX_KEY_LEN check.

Mitigation direction

  • Update affected Linux kernels to versions containing the referenced stable commits.
  • Prioritize systems using libceph or Ceph-related kernel functionality.
  • Check Linux distribution advisories for backported fixes and package-specific guidance.
  • If patching is delayed, follow vendor guidance for reducing libceph exposure.

Validation and detection

  • Inventory Linux kernel versions across affected environments.
  • Identify hosts using libceph or Ceph-related kernel functionality.
  • Confirm the running kernel includes the CEPH_MAX_KEY_LEN enforcement fix.
  • Check distribution security advisories for CVE-2026-43304 status.
Prepared
Confidence
medium
Sources
9

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2026-43304 mapping review

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
9.8 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
0ADP providers
8Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
9.8CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

9.8Critical
CVSS 3.1 vector shape for CVE-2026-43304Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxcd1a677cad994021b19665ed476aea63f5d54f31, cd1a677cad994021b19665ed476aea63f5d54f31, cd1a677cad994021b19665ed476aea63f5d54f31, cd1a677cad994021b19665ed476aea63f5d54f31, cd1a677cad994021b19665ed476aea63f5d54f31, cd1a677cad994021b19665ed476aea63f5d54f31, cd1a677cad994021b19665ed476aea63f5d54f31unaffected
LinuxLinux5.11, 0, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.16, 6.19.6, 7.0affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.