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CVE Record

CVE-2025-21762: arp: use RCU protection in arp_xmit()

In the Linux kernel, the following vulnerability has been resolved: arp: use RCU protection in arp_xmit() arp_xmit() can be called without RTNL or RCU protection. Use RCU protection to avoid potential UAF.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2025-21762 is a Linux kernel memory-safety flaw in ARP transmission handling. A local low-privileged attacker could potentially trigger a use-after-free condition, with high impact to confidentiality, integrity, and availability. Treat this as important for Linux fleets, especially systems running affected kernel lines.

Executive priority

High priority for Linux estate patching. The risk is local rather than remote, but kernel-level compromise can have severe business impact on shared systems, container hosts, and critical infrastructure.

Technical view

The flaw is in arp_xmit(), which can be called without RTNL or RCU protection. The kernel fix adds RCU protection to avoid a potential use-after-free. The CVE is classified as CWE-416 with CVSS 3.1 score 7.8, local attack vector, low complexity, and low privileges required.

Likely exposure

Exposure is likely on Linux systems running affected kernel versions identified in the CVE data, including listed 4.4, 5.4, 5.10, 5.15, 6.1, 6.6, 6.12, 6.13, and 6.14 lines before applicable fixes.

Exploitation context

The source bundle does not show CISA KEV listing or other evidence of active exploitation. The attack vector is local, so exposure is most relevant where untrusted users, workloads, containers, or shared-host access can reach the affected kernel.

Researcher notes

Focus validation on kernel lineage and whether the arp_xmit RCU protection patch is present. The CVE data gives broad affected kernel lines but not complete distribution-specific fixed versions, so rely on vendor package advisories for final status.

Mitigation direction

  • Apply kernel updates from your Linux distribution or vendor.
  • Prioritize multi-user, container-host, and shared compute systems.
  • Review Debian LTS and vendor advisories where applicable.
  • For appliances, confirm OEM firmware includes the upstream kernel fix.
  • Restrict local shell and workload access where patching is delayed.

Validation and detection

  • Inventory Linux kernel versions across servers and appliances.
  • Compare running kernels against vendor fixed-package guidance.
  • Confirm applicable upstream stable commits are present in patched kernels.
  • Check Debian LTS advisories for package-specific remediation status.
  • Document any systems requiring vendor firmware rather than OS packages.
Prepared
Confidence
high
Sources
12

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

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-416: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2025-21762 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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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
3ADP providers
13Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: total

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:H1.85.9CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2025-21762Attack 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.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc
CVECVE Program Container
siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux29a26a56803855a79dbd028cd61abee56237d6e5, 29a26a56803855a79dbd028cd61abee56237d6e5, 29a26a56803855a79dbd028cd61abee56237d6e5, 29a26a56803855a79dbd028cd61abee56237d6e5, 29a26a56803855a79dbd028cd61abee56237d6e5, 29a26a56803855a79dbd028cd61abee56237d6e5, 29a26a56803855a79dbd028cd61abee56237d6e5, 29a26a56803855a79dbd028cd61abee56237d6e5unaffected
LinuxLinux4.4, 0, 5.4.291, 5.10.235, 5.15.179, 6.1.129, 6.6.79, 6.12.16, 6.13.4, 6.14affected
Weakness

CWE details

CWE-416

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

CWE-416 · source CWE mapping

Use After Free

Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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