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CVE Record

CVE-2025-40135: ipv6: use RCU in ip6_xmit()

In the Linux kernel, the following vulnerability has been resolved: ipv6: use RCU in ip6_xmit() Use RCU in ip6_xmit() in order to use dst_dev_rcu() to prevent possible UAF.

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 IPv6 transmit-path flaw can use a network-device object after it has been freed. The supplied CVSS score is 8.1 because successful exploitation could affect confidentiality, integrity, and availability without credentials or user interaction, although exploitation is rated high complexity.

Executive priority

Treat this as a high-priority patching issue, not a confirmed emergency exploitation event. Promptly identify affected internet-facing and critical Linux systems, validate vendor-specific fixes, and track completion. Escalate if exploitation evidence emerges or vulnerable systems cannot be updated.

Technical view

ip6_xmit() could access its destination device without the required read-copy-update protection, creating a possible use-after-free during concurrent object lifetime changes. The kernel fix applies RCU and dst_dev_rcu(). The supplied vector is network-reachable, unauthenticated, and high complexity, but the sources provide no exploit mechanics.

Likely exposure

Systems running the explicitly listed affected Linux releases may be exposed, particularly when using IPv6. The bundle names 4.13, 6.1.167, 6.6.130, 6.12.78, 6.17.3, and 6.18, but provides insufficient context to infer every affected range or downstream distribution build.

Exploitation context

The bundle marks this CVE as absent from KEV and provides no cited evidence of active exploitation or a public exploit. Network reachability and no required privileges increase concern, while high attack complexity reduces likely opportunistic exploitation. Actual exploitability depends on triggering the relevant concurrency condition.

Researcher notes

The record describes a possible use-after-free prevented by adding RCU protection in ip6_xmit(). Five stable-kernel commit references are supplied, apparently covering different maintained branches. Exact vulnerable commit ranges, triggering race conditions, exploit reliability, and downstream backport status are not established in the bundle.

Mitigation direction

  • Apply a supported kernel or distribution update incorporating the applicable cited stable fix.
  • Reboot systems into the remediated kernel after installation.
  • If updating is delayed, consult the kernel or system vendor for supported mitigations.
  • Prioritize exposed, IPv6-capable, business-critical systems for remediation.

Validation and detection

  • Inventory running kernel builds and vendor package revisions on IPv6-capable systems.
  • Compare exact builds against vendor advisories and the applicable stable-fix lineage.
  • Confirm each updated system is running the remediated kernel after reboot.
  • Check vulnerability scanners for reliable build-level detection rather than version-only assumptions.
Prepared
Confidence
medium
Sources
7

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.

ATT&CK lookup starting points

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CVE-2025-40135 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
2ADP providers
8Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical 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
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-2025-40135Attack 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.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36, 4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36, 4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36, 4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36, 4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36unaffected
LinuxLinux4.13, 0, 6.1.167, 6.6.130, 6.12.78, 6.17.3, 6.18affected
Weakness

CWE details

No CWE listed

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