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NVD / CVE Program· CNA Linux

CVE-2026-43067: ext4: handle wraparound when searching for blocks for indirect mapped blocks

Noroxi assessment

Priority: Monitor (action score 39/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.50% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 12624c5b724a81e14e532972b40d863b0de3b7d1, 2a368ccddfc492a0aa951e2caef2985f20e96503, 4bec4a498ce86314d470ae6144120461f2138c29.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 12624c5b724a81e14e532972b40d863b0de3b7d1, 2a368ccddfc492a0aa951e2caef2985f20e96503, 4bec4a498ce86314d470ae6144120461f2138c29 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: ext4: handle wraparound when searching for blocks for indirect mapped blocks Commit 4865c768b563 ("ext4: always allocate blocks only from groups inode can use") restricts what blocks will be allocated for indirect block based files to block numbers that fit within 32-bit block numbers. However, when using a review bot running on the latest Gemini LLM to check this commit when backporting into an LTS based kernel, it raised this concern: If ac->ac_g_ex.fe_group is >= ngroups (for instance, if the goal group was populated via stream allocation from s_mb_last_groups), then start will be >= ngroups. Does this allow allocating blocks beyond the 32-bit limit for indirect block mapped files? The commit message mentions that ext4_mb_scan_groups_linear() takes care to not select unsupported groups. However, its loop uses group = *start, and the very first iteration will call ext4_mb_scan_group() with this unsupported group because next_linear_group() is only called at the end of the iteration. After reviewing the code paths involved and considering the LLM review, I determined that this can happen when there is a file system where some files/directories are extent-mapped and others are indirect-block mapped. To address this, add a safety clamp in ext4_mb_scan_groups().

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
May 5, 2026
Updated
Oct 19, 2026
EPSS
0.5% · 43th percentile

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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When you'll hear from us

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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel5.15.203 and later · before 5.16
  • linux linux kernel6.6.130 and later · before 6.6.134
  • linux linux kernel6.12.77 and later · before 6.12.80
  • linux linux kernel6.18.14 and later · before 6.18.21
  • linux linux kernel6.19.4 and later · before 6.19.11
  • linux linux kernel6.1.167

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 16fce6b6c0b247258c6c217fce5a48abf50f6964affected
    • 9d89b9d55e25cb340c5b4b769876edc551b7a9ff and later · before f89bba144938921a2249237ad04a0183ff3f8930affected · git
    • 1b0edd6022a3f44ce87fea9959a9310f4628fbea and later · before 83170a05908b6cf2fb3235d3065bf613ff866f3caffected · git
    • 9eea2f57d11b30049ff996ac3eff6e0dc8089e5f and later · before 4bec4a498ce86314d470ae6144120461f2138c29affected · git
    • 34c803edc0b3365a42efcf9815acab63b4cf54e0 and later · before 12624c5b724a81e14e532972b40d863b0de3b7d1affected · git
    • 321ed8d559c951e71ad2d2d69a4cf0445644e865 and later · before 2a368ccddfc492a0aa951e2caef2985f20e96503affected · git
    • 4865c768b563deff1b6a6384e74a62f143427b42 and later · before bb81702370fad22c06ca12b6e1648754dbc37e0faffected · git
    • 5.15.203 and later · before 5.16affected · semver
    • 6.1.167 and later · before 6.1.168affected · semver
    • 6.6.130 and later · before 6.6.134affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:14linuxbefore 6.19.11-16.19.11-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-43064May 5, 2026 · dmaengine: idxd: Fix not releasing workqueue on .release()
    22Monitor
  • ← EarlierCVE-2026-43065May 5, 2026 · ext4: always drain queued discard work in ext4_mb_release()
    22Monitor
  • Later →CVE-2026-43068May 5, 2026 · ext4: avoid allocate block from corrupted group in ext4_mb_find_by_goal()
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux12624c5b724a81e14e532972b40d863b0de3b7d1Vendor (CNA)
Linux Linux2a368ccddfc492a0aa951e2caef2985f20e96503Vendor (CNA)
Linux Linux4bec4a498ce86314d470ae6144120461f2138c29Vendor (CNA)
Linux Linux5.16Vendor (CNA)
Linux Linux6.1.168Vendor (CNA)
Linux Linux6.12.80Vendor (CNA)
Linux Linux6.18.21Vendor (CNA)
Linux Linux6.19.11Vendor (CNA)
Linux Linux6.6.134Vendor (CNA)
Linux Linux83170a05908b6cf2fb3235d3065bf613ff866f3cVendor (CNA)
Linux Linuxbb81702370fad22c06ca12b6e1648754dbc37e0fVendor (CNA)
Linux Linuxf89bba144938921a2249237ad04a0183ff3f8930Vendor (CNA)
debian:linux6.19.11-1 · Debian:14Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-6428681 days apartKVM: arm64: Clear __hyp_running_vcpu when flushing the pKVM hyp vCPU
    32Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-822 · Untrusted Pointer Dereference

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records