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CVE Record

CVE-2025-40133: mptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active_enable().

In the Linux kernel, the following vulnerability has been resolved: mptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active_enable(). mptcp_active_enable() is called from subflow_finish_connect(), which is icsk->icsk_af_ops->sk_rx_dst_set() and it's not always under RCU. Using sk_dst_get(sk)->dev could trigger UAF. Let's use __sk_dst_get() and dst_dev_rcu().

HighCVSS 8.1Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux kernel flaw in Multipath TCP handling can access network-device memory after it has been freed. Under specific timing conditions, a remote, unauthenticated attacker could potentially compromise confidentiality, integrity, or availability. Exploitation appears difficult, but affected systems warrant prompt review because the supplied CVSS score is 8.1.

Executive priority

Treat as a high-priority patch-management issue, especially for exposed systems using MPTCP. Schedule vendor-supported kernel updates promptly, while recognizing that the supplied evidence shows high exploitation complexity and no confirmed active attacks.

Technical view

mptcp_active_enable() may call sk_dst_get(sk)->dev without the required RCU protection when reached through subflow_finish_connect(). This can trigger a use-after-free. The cited kernel changes replace that access with __sk_dst_get() and dst_dev_rcu(). The supplied CVSS vector indicates network reachability, high complexity, no privileges, and no user interaction.

Likely exposure

Exposure is limited to Linux systems running affected kernel versions and exercising the vulnerable MPTCP connection path. The bundle identifies 6.12, 6.12.55, 6.17.3, and 6.18 as affected, but its version metadata is incomplete or ambiguous; confirm status with the distribution or kernel vendor.

Exploitation context

The bundle does not identify known active exploitation, and the CVE is not listed as KEV. The high attack-complexity rating suggests exploitation depends on difficult timing or state conditions. No public proof of concept or reliable exploitation evidence is established by the supplied sources.

Researcher notes

The security defect is an RCU-lifetime violation involving destination and network-device access in the MPTCP receive-destination callback path. The sources establish the code-level correction, but do not establish exploit reliability, affected configurations, proof-of-concept availability, or precise downstream distribution package ranges.

Mitigation direction

  • Check distribution and kernel-vendor advisories for affected package versions and approved updates.
  • Upgrade to a supported kernel release containing the applicable cited stable fix.
  • Prioritize internet-facing or untrusted-network systems where MPTCP is enabled or used.
  • Apply normal change controls and reboot if required to activate the updated kernel.

Validation and detection

  • Record the running kernel version and distribution package release on each Linux asset.
  • Determine whether MPTCP is enabled or operationally used on potentially affected systems.
  • Map vendor package versions to the cited upstream fixes; do not rely solely on version strings.
  • After remediation, confirm the fixed kernel is running rather than merely installed.
  • Monitor vendor advisories for clarified affected-version boundaries and exploitation evidence.
Prepared
Confidence
medium
Sources
5

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-2025-40133 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.1 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:H/PR:N/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
4Source 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
8.1CVSS 3.1HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H2.25.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

8.1High
CVSS 3.1 vector shape for CVE-2025-40133Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:H/PR:N/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
LinuxLinux27069e7cb3d1cea9377069266acf19b9cc5ad0ae, 27069e7cb3d1cea9377069266acf19b9cc5ad0ae, 27069e7cb3d1cea9377069266acf19b9cc5ad0aeunaffected
LinuxLinux6.12, 0, 6.12.55, 6.17.3, 6.18affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.