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CVE Record

CVE-2026-43166: erofs: fix interlaced plain identification for encoded extents

In the Linux kernel, the following vulnerability has been resolved: erofs: fix interlaced plain identification for encoded extents Only plain data whose start position and on-disk physical length are both aligned to the block size should be classified as interlaced plain extents. Otherwise, it must be treated as shifted plain extents. This issue was found by syzbot using a crafted compressed image containing plain extents with unaligned physical lengths, which can cause OOB read in z_erofs_transform_plain().

HighCVSS 7.1Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A malformed compressed EROFS filesystem image can make the Linux kernel read outside an intended memory boundary. Triggering requires local handling of a crafted image and user interaction. Successful exploitation could expose kernel memory or crash the system, but the supplied sources provide no evidence of active exploitation.

Executive priority

Prioritize systems that handle externally supplied filesystem images or require high availability. Schedule prompt kernel updates after compatibility testing. Broader emergency action is not supported by the supplied evidence because exploitation requires local image handling and active exploitation is not documented.

Technical view

EROFS incorrectly classified certain plain extents as interlaced when their physical lengths were not block-aligned. Those extents should be treated as shifted. A crafted compressed image can therefore cause an out-of-bounds read in z_erofs_transform_plain(), affecting confidentiality and availability without a documented integrity impact.

Likely exposure

Exposure is most likely on affected Linux systems that process or mount compressed EROFS images from untrusted sources. The supplied version data includes 6.15, 6.18.16, 6.19.6, and 7.0, but does not clearly map every affected or fixed downstream distribution build.

Exploitation context

The CVSS vector describes a local, low-complexity attack requiring no privileges but requiring user interaction. Syzbot discovered the flaw with a crafted image. The CVE is not listed as KEV, and the supplied sources do not report exploitation in the wild or a public weaponized exploit.

Researcher notes

The security boundary failure is extent classification: interlaced plain requires both an aligned start and aligned on-disk physical length. Otherwise, shifted-plain handling is required. The source bundle provides three stable commits but incomplete release-to-fix mapping, so downstream vendor backport status must be verified independently.

Mitigation direction

  • Update to a vendor-supported kernel containing the applicable cited stable fix.
  • Check distribution guidance for exact affected and fixed package versions.
  • Until updated, avoid processing or mounting untrusted compressed EROFS images.
  • Restrict who can introduce filesystem images to exposed systems.

Validation and detection

  • Inventory Linux kernel builds and determine where EROFS is enabled or used.
  • Map each distribution kernel package to its vendor's CVE status.
  • Confirm the installed source or package includes the applicable cited fix.
  • Review workflows that ingest compressed EROFS images from untrusted sources.
  • After updating, verify the new kernel is running on each system.
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

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CVE-2026-43166 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.1 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/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
7.1CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H1.85.2Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.1High
CVSS 3.1 vector shape for CVE-2026-43166Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/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
LinuxLinux1d191b4ca51d73699cb127386b95ac152af2b930, 1d191b4ca51d73699cb127386b95ac152af2b930, 1d191b4ca51d73699cb127386b95ac152af2b930unaffected
LinuxLinux6.15, 0, 6.18.16, 6.19.6, 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.