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CVE Record

CVE-2026-23066: rxrpc: Fix recvmsg() unconditional requeue

In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix recvmsg() unconditional requeue If rxrpc_recvmsg() fails because MSG_DONTWAIT was specified but the call at the front of the recvmsg queue already has its mutex locked, it requeues the call - whether or not the call is already queued. The call may be on the queue because MSG_PEEK was also passed and so the call was not dequeued or because the I/O thread requeued it. The unconditional requeue may then corrupt the recvmsg queue, leading to things like UAFs or refcount underruns. Fix this by only requeuing the call if it isn't already on the queue - and moving it to the front if it is already queued. If we don't queue it, we have to put the ref we obtained by dequeuing it. Also, MSG_PEEK doesn't dequeue the call so shouldn't call rxrpc_notify_socket() for the call if we didn't use up all the data on the queue, so fix that also.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-23066 is a Linux kernel rxrpc bug that can corrupt an internal receive queue and lead to use-after-free or reference count errors. The published score is high because a local low-privileged user may be able to impact confidentiality, integrity, and availability. No active exploitation is stated in the supplied sources.

Executive priority

Treat this as a high-priority kernel update for shared or multi-tenant Linux environments. It is not reported as actively exploited in the supplied sources, but the possible kernel memory corruption impact makes delayed patching risky where local users or workloads are not fully trusted.

Technical view

rxrpc_recvmsg() could unconditionally requeue a call after a nonblocking recvmsg path failed on a locked call. If that call was already queued, including MSG_PEEK or I/O thread requeue cases, the queue could be corrupted, causing UAFs or refcount underruns. Stable kernel commits change requeue handling and MSG_PEEK notification behavior.

Likely exposure

Systems running Linux kernels with the affected rxrpc code before the referenced stable fixes are the relevant exposure. The CVSS vector is local, low complexity, low privileges, and no user interaction. Exposure is most relevant where untrusted local users, containers, or workloads can reach kernel rxrpc paths.

Exploitation context

The source bundle does not state public exploit availability or active exploitation, and KEV is false. The vulnerability is local rather than remote in the supplied CVSS vector. Practical exploitability is not established by the provided evidence, but kernel memory-safety outcomes justify prompt remediation.

Researcher notes

The key behavior is unconditional recvmsg queue requeue when the call may already be queued. The fix conditionally requeues, moves already queued calls to the front, drops the extra reference when not queued, and corrects MSG_PEEK notification behavior. Sources do not provide exploit proof or operational detections.

Mitigation direction

  • Update affected Linux kernels to builds containing the referenced stable rxrpc fixes.
  • Check distribution kernel advisories for the backported fix status.
  • Prioritize multi-user systems, container hosts, and shared compute environments.
  • If rxrpc is unnecessary, review vendor-supported options to reduce exposure.
  • Avoid relying on version strings alone when vendors backport patches.

Validation and detection

  • Inventory Linux kernel versions and distribution patch levels across hosts.
  • Confirm whether deployed kernels include one of the referenced stable commits or vendor backports.
  • Review local-user and container-host exposure where untrusted code can run.
  • Monitor vendor advisories for any revised affected-version or mitigation guidance.
  • Track remediation evidence in vulnerability management records.
Prepared
Confidence
high
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

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CVE-2026-23066 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/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
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
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2026-23066Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux540b1c48c37ac0ad66212004db21e1ff7e2d78be, 540b1c48c37ac0ad66212004db21e1ff7e2d78be, 540b1c48c37ac0ad66212004db21e1ff7e2d78be, 540b1c48c37ac0ad66212004db21e1ff7e2d78be, 540b1c48c37ac0ad66212004db21e1ff7e2d78be, 540b1c48c37ac0ad66212004db21e1ff7e2d78be, 540b1c48c37ac0ad66212004db21e1ff7e2d78beunaffected
LinuxLinux4.11, 0, 5.10.258, 5.15.209, 6.1.175, 6.6.130, 6.12.78, 6.18.8, 6.19affected
Weakness

CWE details

No CWE listed

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