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CVE Record

CVE-2026-23272: netfilter: nf_tables: unconditionally bump set->nelems before insertion

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: unconditionally bump set->nelems before insertion In case that the set is full, a new element gets published then removed without waiting for the RCU grace period, while RCU reader can be walking over it already. To address this issue, add the element transaction even if set is full, but toggle the set_full flag to report -ENFILE so the abort path safely unwinds the set to its previous state. As for element updates, decrement set->nelems to restore it. A simpler fix is to call synchronize_rcu() in the error path. However, with a large batch adding elements to already maxed-out set, this could cause noticeable slowdown of such batches.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-23272 is a high-severity Linux kernel flaw in nf_tables, part of netfilter firewall handling. A local attacker with required privileges could trigger unsafe element removal and potentially gain high-impact control over confidentiality, integrity, or availability. The provided sources do not show active exploitation.

Executive priority

Treat as a near-term patching priority for Linux fleets, especially shared systems and container hosts. It is not currently KEV-listed in the provided sources, so emergency response depends on local exposure and vendor advisories.

Technical view

The bug is an RCU lifetime issue in nf_tables set insertion. When a set is full, an element can be published and then removed without waiting for an RCU grace period while readers may still traverse it. Linux stable commits change transaction handling so abort unwinds safely.

Likely exposure

Systems running affected Linux kernels with nf_tables/netfilter available are the likely exposure. The provided version data is incomplete and ambiguous, so confirm exposure through distribution kernel advisories, package changelogs, and whether referenced stable commits are present.

Exploitation context

The CVSS vector is local, low complexity, low privileges, no user interaction, with high CIA impact. The source bundle marks CISA KEV as false and provides no cited evidence of exploitation in the wild or public exploit availability.

Researcher notes

Focus review on nf_tables set insertion failure handling and RCU reader safety. The provided description identifies unsafe publish-remove behavior when sets are full, fixed by preserving transaction unwinding rather than adding synchronize_rcu in the error path.

Mitigation direction

  • Update Linux kernels through your distribution security channel.
  • Confirm the kernel includes one of the referenced stable fixes.
  • Prioritize multi-user hosts, container platforms, and internet-facing workloads with local shell access paths.
  • Check vendor guidance if immediate patching is not available.
  • Limit untrusted local access where operationally possible until patched.

Validation and detection

  • Inventory Linux kernel versions across servers, containers hosts, and appliances.
  • Review distribution advisories for CVE-2026-23272 fix status.
  • Verify package changelogs include the nf_tables set->nelems RCU fix.
  • Check whether nf_tables/netfilter functionality is enabled or loaded.
  • Track exceptions where vendor kernels backport fixes without changing upstream version numbers.
Prepared
Confidence
medium
Sources
8

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-2026-23272 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
7Source 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-2026-23272Attack 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
LinuxLinux35d0ac9070ef619e3bf44324375878a1c540387b, 35d0ac9070ef619e3bf44324375878a1c540387b, 35d0ac9070ef619e3bf44324375878a1c540387b, 35d0ac9070ef619e3bf44324375878a1c540387b, 35d0ac9070ef619e3bf44324375878a1c540387b, 35d0ac9070ef619e3bf44324375878a1c540387b, fefdd79403e89b0c673965343b92e2e01e2713a8, 4.9.33unaffected
LinuxLinux4.10, 0, 6.1.177, 6.6.141, 6.12.91, 6.18.17, 6.19.7, 7.0affected
Weakness

CWE details

No CWE listed

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