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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

A flaw in Linux’s RxRPC receive handling can corrupt a kernel queue when specific nonblocking or peek operations overlap. A low-privileged local user could potentially crash the system or compromise kernel-level confidentiality and integrity. The supplied evidence does not show remote reachability or active exploitation.

Executive priority

Treat as a high-priority kernel update for shared or locally accessible Linux systems. Schedule prompt remediation through normal kernel maintenance, accelerating systems with untrusted local users. Internet exposure alone does not increase urgency because the supplied CVSS assessment identifies a local attack vector.

Technical view

rxrpc_recvmsg() could requeue a call already present on the receive queue after mutex contention, corrupting queue state and causing use-after-free conditions or reference-count underruns. The correction conditionally requeues or moves the call, releases the appropriate reference, and fixes MSG_PEEK notification behavior. CVSS 3.1 is 7.8 with local, low-privilege attack requirements.

Likely exposure

Exposure is most relevant to systems running affected Linux releases where local users or workloads can exercise RxRPC receive operations. The supplied affected-version entries include 4.11 and listed releases through 6.19, but they do not provide sufficiently clear boundaries for reliable distribution-package mapping.

Exploitation context

The CVSS vector requires local access and low privileges, without user interaction. Successful exploitation could affect all three security properties at kernel scope. KEV is false, and no supplied source establishes public or active exploitation.

Researcher notes

The vulnerable state involves duplicate or unconditional receive-queue insertion during nonblocking mutex contention, including interactions with MSG_PEEK and I/O-thread requeueing. Reported consequences are queue corruption, use-after-free, and reference-count underruns. The bundle supplies multiple stable commits but no definitive branch-to-fixed-version mapping, proof of exploitation, or affected distribution list.

Mitigation direction

  • Apply Linux or distribution kernel updates containing the applicable cited stable fix.
  • Reboot affected systems into the corrected kernel after installation.
  • Prioritize shared, multi-user, and locally accessible systems where RxRPC functionality is used.
  • If updates are delayed, consult distribution guidance for supported exposure-reduction measures.

Validation and detection

  • Inventory running kernel versions and compare them with distribution advisories for CVE-2026-23066.
  • Determine whether RxRPC functionality is present and used by local workloads.
  • Confirm the installed kernel includes an applicable cited commit or documented vendor backport.
  • After rebooting, verify the corrected kernel is the actively running version.
  • Review kernel crash and memory-safety alerts for related symptoms; absence does not prove safety.
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

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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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