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CVE Record

CVE-2026-43074: eventpoll: defer struct eventpoll free to RCU grace period

In the Linux kernel, the following vulnerability has been resolved: eventpoll: defer struct eventpoll free to RCU grace period In certain situations, ep_free() in eventpoll.c will kfree the epi->ep eventpoll struct while it still being used by another concurrent thread. Defer the kfree() to an RCU callback to prevent UAF.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux kernel race can free event-polling memory while another thread still uses it. A local, low-privileged user could potentially trigger severe confidentiality, integrity, or availability impact. The supplied CVSS score is 7.8 (high).

Executive priority

Treat as a high-priority kernel update, especially on shared servers, developer platforms, and untrusted-workload hosts. It is not presented as remotely exploitable or actively exploited, so prioritize according to local-code exposure and normal emergency kernel-change controls.

Technical view

Concurrent activity can cause ep_free() to release an eventpoll structure still referenced by another thread, creating a use-after-free condition. The kernel fix defers memory release through an RCU callback, ensuring an RCU grace period before reclamation.

Likely exposure

Systems running affected Linux kernels and allowing untrusted or low-privileged local code are the primary concern. The bundle's version data is ambiguous, so determine exposure using distribution advisories and whether the running kernel contains an applicable referenced fix.

Exploitation context

The CVSS vector describes local access, low privileges, low complexity, and no user interaction. The bundle marks this CVE as absent from KEV and provides no evidence of active exploitation or a public exploit. Absence from KEV does not prove exploitation is impossible.

Researcher notes

The evidence establishes a concurrency-driven use-after-free involving epi->ep during ep_free(). The remediation changes reclamation timing rather than removing eventpoll functionality. The bundle does not identify trigger conditions beyond certain concurrent situations, exploitation outcomes, public proof-of-concept availability, or reliable distribution-specific affected ranges.

Mitigation direction

  • Install a vendor-supported kernel update containing the applicable eventpoll RCU fix.
  • Reboot systems into the updated kernel after installation.
  • Prioritize multi-user hosts and systems executing untrusted local workloads.
  • Consult Linux distribution guidance because the supplied affected-version boundaries are unclear.

Validation and detection

  • Record each system's running kernel release, build, and distribution package revision.
  • Map kernel packages to distribution advisories or the referenced stable commits.
  • Confirm the installed update contains the eventpoll RCU fix.
  • Verify each system rebooted into the corrected kernel, not merely installed it.
  • Document unresolved systems where vendor fix status remains unavailable.
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-2026-43074 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-2026-43074Attack 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
LinuxLinuxf2451def095c1743adcfcb0cb5dadc86034e162a, a1f93804449d13f97dabd4b996817de4bf1ed67a, 58c9b016e12855286370dfb704c08498edbc857a, 58c9b016e12855286370dfb704c08498edbc857a, 58c9b016e12855286370dfb704c08498edbc857a, 58c9b016e12855286370dfb704c08498edbc857a, 58c9b016e12855286370dfb704c08498edbc857aunaffected
LinuxLinux6.4, 0, 6.6.136, 6.12.83, 6.18.24, 6.19.14, 7.0affected
Weakness

CWE details

No CWE listed

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