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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

CVE-2026-22991 is a Linux kernel libceph flaw that can crash the kernel through a NULL pointer dereference after partial memory allocation failure. The business impact is availability: affected Linux hosts using reachable Ceph kernel functionality could be disrupted. The sources do not show data theft, integrity impact, or confirmed exploitation.

Executive priority

Treat as a high-priority availability risk for Linux environments that use Ceph. Patch through standard kernel channels after testing. No source evidence supports emergency exploitation response, but unauthenticated network availability impact warrants timely remediation.

Technical view

free_choose_arg_map() can iterate over arg_map->args when that pointer is NULL because arg_map->size is set before allocation completes. The upstream fix adds pointer checks before iteration. CVSS 3.1 is 7.5: network attack vector, low complexity, no privileges, no user interaction, availability high.

Likely exposure

Exposure is most relevant to Linux systems running affected kernel versions where libceph functionality is present and reachable. Prioritize hosts using Ceph-related kernel client functionality. The supplied version data is incomplete in flattened form, so validate exact kernel builds against the CVE record and referenced stable commits.

Exploitation context

The source bundle marks KEV as false and provides no cited evidence of active exploitation. The CVSS vector indicates network-reachable, unauthenticated availability impact, but the bundle does not provide exploit mechanics, proof-of-concept status, or real-world attack reports.

Researcher notes

Key issue is defensive cleanup after partial allocation failure. The patch hardens free_choose_arg_map() by checking pointers before walking allocation-dependent structures. The bundle does not include CWE mapping, exploit details, or distribution package names, so avoid over-scoping beyond Linux/libceph exposure.

Mitigation direction

  • Update affected Linux kernels to versions containing the referenced stable fixes.
  • Prioritize Ceph-using hosts and systems where libceph is reachable over the network.
  • Check Linux vendor advisories for distribution-specific fixed kernel packages.
  • If immediate update is impossible, reduce exposure of Ceph-related services where operationally feasible.

Validation and detection

  • Inventory kernel versions across Linux hosts and compare with vendor fixed builds.
  • Identify systems using Ceph or libceph-related kernel functionality.
  • Confirm deployed kernels include one of the referenced stable commits or vendor backports.
  • Monitor for unexpected kernel crashes on Ceph-capable systems until patched.
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
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
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.

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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