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CVE Record

CVE-2026-22991: libceph: make free_choose_arg_map() resilient to partial allocation

In the Linux kernel, the following vulnerability has been resolved: libceph: make free_choose_arg_map() resilient to partial allocation free_choose_arg_map() may dereference a NULL pointer if its caller fails after a partial allocation. For example, in decode_choose_args(), if allocation of arg_map->args fails, execution jumps to the fail label and free_choose_arg_map() is called. Since arg_map->size is updated to a non-zero value before memory allocation, free_choose_arg_map() will iterate over arg_map->args and dereference a NULL pointer. To prevent this potential NULL pointer dereference and make free_choose_arg_map() more resilient, add checks for pointers before iterating.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux kernel libceph cleanup flaw can dereference a null pointer after memory allocation only partially succeeds. The resulting kernel fault could interrupt affected systems or storage-dependent services. The supplied CVSS score is 7.5, reflecting high availability impact without stated confidentiality or integrity impact.

Executive priority

Treat this as a high-priority availability issue for systems using libceph, especially business-critical storage workloads. Establish exposure through vendor version mapping, patch affected kernels promptly, and monitor for related kernel faults. Broader emergency action is not supported by the supplied exploitation evidence.

Technical view

In decode_choose_args(), arg_map->size can become non-zero before arg_map->args is allocated. If allocation fails, free_choose_arg_map() may iterate through the null args pointer. The referenced stable changes add pointer checks before iteration, making cleanup safe after partial allocation.

Likely exposure

Exposure is most likely on affected Linux kernels where libceph processes choose arguments. The CVSS vector characterizes the attack path as remote and unauthenticated, but the description does not identify the precise externally reachable service boundary. Distribution-specific kernel exposure cannot be determined from the supplied version data alone.

Exploitation context

The bundle marks this CVE as absent from KEV and provides no evidence of active exploitation or a public exploit. That does not prove exploitation is impossible. The documented outcome is availability loss through a potential kernel null-pointer dereference.

Researcher notes

The failure requires a partial-allocation cleanup path: size is initialized before args allocation, then cleanup trusts size and dereferences args. The fix hardens cleanup with pointer checks. The supplied affected-version entries are not clear ranges and include repeated commit identifiers, limiting confident branch and distribution mapping.

Mitigation direction

  • Upgrade to a Linux kernel build containing the applicable referenced stable fix.
  • Consult the Linux distribution or kernel vendor for packaged-version applicability and update guidance.
  • Prioritize systems actively using libceph or Ceph-backed storage.
  • If upgrading is delayed, request a vendor-supported workaround; none is named in the sources.

Validation and detection

  • Inventory running kernel versions and map them through applicable vendor advisories.
  • Identify systems where libceph is present and actively used.
  • Confirm the installed kernel includes the applicable referenced pointer-check fix.
  • Monitor kernel fault records for free_choose_arg_map or decode_choose_args failures.
  • Perform vendor-approved Ceph storage regression testing after updating.
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-2026-22991 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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
1ADP providers
8Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical 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
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-22991Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux5cf9c4a9959b6273675310d14a834ef14fbca37c, 5cf9c4a9959b6273675310d14a834ef14fbca37c, 5cf9c4a9959b6273675310d14a834ef14fbca37c, 5cf9c4a9959b6273675310d14a834ef14fbca37c, 5cf9c4a9959b6273675310d14a834ef14fbca37c, 5cf9c4a9959b6273675310d14a834ef14fbca37c, 5cf9c4a9959b6273675310d14a834ef14fbca37cunaffected
LinuxLinux4.13, 0, 5.10.248, 5.15.198, 6.1.161, 6.6.121, 6.12.66, 6.18.6, 6.19affected
Weakness

CWE details

No CWE listed

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