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CVE Record

CVE-2024-26689: ceph: prevent use-after-free in encode_cap_msg()

In the Linux kernel, the following vulnerability has been resolved: ceph: prevent use-after-free in encode_cap_msg() In fs/ceph/caps.c, in encode_cap_msg(), "use after free" error was caught by KASAN at this line - 'ceph_buffer_get(arg->xattr_buf);'. This implies before the refcount could be increment here, it was freed. In same file, in "handle_cap_grant()" refcount is decremented by this line - 'ceph_buffer_put(ci->i_xattrs.blob);'. It appears that a race occurred and resource was freed by the latter line before the former line could increment it. encode_cap_msg() is called by __send_cap() and __send_cap() is called by ceph_check_caps() after calling __prep_cap(). __prep_cap() is where arg->xattr_buf is assigned to ci->i_xattrs.blob. This is the spot where the refcount must be increased to prevent "use after free" error.

HighCVSS 8.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A race condition in the Linux Ceph filesystem client can access memory after it has been freed. Successful exploitation could compromise confidentiality, integrity, and availability. Risk is concentrated on systems using affected Linux kernels with Ceph filesystem functionality, rather than every Linux host.

Executive priority

Treat this as a high-priority kernel remediation for Ceph-using systems, especially multi-tenant or business-critical storage environments. It does not warrant assuming organization-wide Linux exposure or active attack without supporting evidence. Patch through supported distribution channels and verify the running kernel afterward.

Technical view

The flaw occurs in fs/ceph/caps.c when encode_cap_msg() obtains a reference to an extended-attribute buffer that handle_cap_grant() may concurrently release. The correction moves the reference increment to __prep_cap(), preventing the buffer from being freed before use. The supplied CVSS 3.1 score is 8.8, requiring low privileges and no user interaction.

Likely exposure

Prioritize Linux systems that mount or otherwise use Ceph filesystems and run an affected kernel. The supplied record identifies affected releases from 2.6.34 through listed 5.10, 5.15, 6.1, 6.6, 6.7, and 6.8 versions. Distribution backports may make version-only assessment unreliable.

Exploitation context

The supplied record does not identify CISA KEV inclusion or provide evidence of active exploitation. Its CVSS vector describes network reachability, low attack complexity, low privileges, no user interaction, and potentially high confidentiality, integrity, and availability impact. Practical exploitability is not established by the supplied sources.

Researcher notes

KASAN detected the use-after-free at ceph_buffer_get(arg->xattr_buf). The reported race is between reference acquisition during capability-message preparation and release in handle_cap_grant(). The fix establishes the reference earlier in __prep_cap(). The bundle does not provide proof of reliable exploitation, affected configuration prerequisites beyond the Ceph code path, or observed attacks.

Mitigation direction

  • Apply vendor-supported kernel updates containing the cited upstream stable fix.
  • Prioritize Ceph filesystem clients and hosts processing untrusted or multi-tenant Ceph activity.
  • If immediate patching is impossible, reduce unnecessary access to affected Ceph-mounted systems.
  • Check distribution advisories because maintained kernels may contain backported fixes under unchanged version numbers.

Validation and detection

  • Inventory kernel versions and identify hosts using the Linux Ceph filesystem client.
  • Confirm installed kernel packages include the applicable cited stable commit or vendor backport.
  • Review kernel logs and monitoring for Ceph-related crashes or memory-safety alerts.
  • Reboot after kernel updates and verify the patched kernel is actively running.
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.

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CVE-2024-26689 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:L/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
2ADP providers
8Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

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
8.8CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H2.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

8.8High
CVSS 3.1 vector shape for CVE-2024-26689Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:L/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.

ADP provider summaries

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux9030aaf9bf0a1eee47a154c316c789e959638b0f, 9030aaf9bf0a1eee47a154c316c789e959638b0f, 9030aaf9bf0a1eee47a154c316c789e959638b0f, 9030aaf9bf0a1eee47a154c316c789e959638b0f, 9030aaf9bf0a1eee47a154c316c789e959638b0f, 9030aaf9bf0a1eee47a154c316c789e959638b0funaffected
LinuxLinux2.6.34, 0, 5.10.210, 5.15.149, 6.1.79, 6.6.18, 6.7.6, 6.8affected
Weakness

CWE details

No CWE listed

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