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NVD / CVE Program· CNA Linux

CVE-2026-64324: udf: validate free block extents against the partition length

HighCVSS 7.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 31/100)

  • 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: 0.16% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 12af328d2ee8d68e81ba612246d0b54b22d23e1f, 335202ab25b01fdd45889ff25eab70864686dea3, 4.20; azl3 kernel 6.6.144.1-1 on Azure Linux 3.0 6.6.145.2-1.

Low priority for now. Upgrade to Linux Linux 12af328d2ee8d68e81ba612246d0b54b22d23e1f, 335202ab25b01fdd45889ff25eab70864686dea3, 4.20; azl3 kernel 6.6.144.1-1 on Azure Linux 3.0 6.6.145.2-1 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: udf: validate free block extents against the partition length udf_free_blocks() checks the logical block number and count against the partition length, but drops the extent offset from that final bound. A crafted extent can pass the guard while logicalBlockNum + offset + count points past the partition, which later indexes past the space bitmap array. A single ftruncate(2) on a file backed by such an extent reliably panics the kernel. This is a local availability issue. On desktop systems where UDisks/polkit allows the active user to mount removable UDF media without CAP_SYS_ADMIN, an unprivileged local user can supply the crafted filesystem and trigger the panic by truncating a writable file on it. Systems that require root or CAP_SYS_ADMIN to mount the image have a higher prerequisite. No confidentiality or integrity impact is claimed: the reproduced primitive is an out-of-bounds read of a bitmap pointer slot followed by a kernel panic. Use the already computed logicalBlockNum + offset + count value for the partition length check. Also make load_block_bitmap() reject an out-of-range block group before indexing s_block_bitmap[], so corrupted callers cannot walk past the flexible array.

Published
Jul 25, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 5th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.8
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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Follow CVE-2026-64324

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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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 kernel4.19.320 and later · before 4.20
  • linux linux kernel5.4.282 and later · before 5.5
  • linux linux kernel5.10.224 and later · before 5.10.261
  • linux linux kernel5.15.165 and later · before 5.15.212
  • linux linux kernel6.1.105 and later · before 6.1.178
  • linux linux kernel6.6.46 and later · before 6.6.145
  • linux linux kernel6.10.5 and later · before 6.12.96
  • linux linux kernel6.13 and later · before 6.18.39
  • linux linux kernel6.19 and later · before 7.1.4

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

    • 097420e48e30f51e8f4f650b5c946f5af63ec1a3, 5def895b42ef16a2da6402818cba8d7ec8ede1ef, 05fb2bf477d3fe5421bd4cb699574737f52bd88b, 6.11affected
    • 934f815345c09c290a9b9a9cfdddc203ec2117e8 and later · before fdd6229d2ae9914c1f25d1041db0f4f312a4fa76affected · git
    • 22cc7323f090646c8cfb5939e6f15bdc2ed3fd27 and later · before b54aee5652fcd7c23a0904a4623ec462c3edc70caffected · git
    • 7c4fa9ebfce69619d132fe703dc2e2cf62a13723 and later · before 12af328d2ee8d68e81ba612246d0b54b22d23e1faffected · git
    • 5cc9745e2ea11aef7d5c9a42bc36f6cd3e1b4cc3 and later · before fb49099206c5c57af28a157249fa7bcb5518f99eaffected · git
    • 56e69e59751d20993f243fb7dd6991c4e522424c and later · before 9442d75429b0c556292a7454fe888d54259f5240affected · git
    • 56e69e59751d20993f243fb7dd6991c4e522424c and later · before 335202ab25b01fdd45889ff25eab70864686dea3affected · git
    • 56e69e59751d20993f243fb7dd6991c4e522424c and later · before be87de7789a82a030a4896bc7683415ec9fa6f2baffected · git
    • 56e69e59751d20993f243fb7dd6991c4e522424c and later · before 5f0419457f89dce1a3f1c8e62a3adf2f39ab8168affected · git
    • 5.10.224 and later · before 5.10.261affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.180-16.1.180-1
Debian:12linux-6.12before 6.12.100-1~deb12u16.12.100-1~deb12u1
Debian:13linuxbefore 6.12.96-16.12.96-1
Debian:14linuxbefore 7.1.4-17.1.4-1

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-2026-64322Jul 25, 2026 · udf: validate sparing table length as an entry count, not a byte count
    31Monitor
  • ← EarlierCVE-2026-64323Jul 25, 2026 · udf: validate VAT header length against the VAT inode size
    28Monitor
  • Later →CVE-2026-64325Jul 25, 2026 · wifi: mt76: mt7921/mt7925: fix NULL dereference in CSA beacon
    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 Linux12af328d2ee8d68e81ba612246d0b54b22d23e1fVendor (CNA)
Linux Linux335202ab25b01fdd45889ff25eab70864686dea3Vendor (CNA)
Linux Linux4.20Vendor (CNA)
Linux Linux5.10.261Vendor (CNA)
Linux Linux5.15.212Vendor (CNA)
Linux Linux5.5Vendor (CNA)
Linux Linux5f0419457f89dce1a3f1c8e62a3adf2f39ab8168Vendor (CNA)
Linux Linux6.1.178Vendor (CNA)
Linux Linux6.11Vendor (CNA)
Linux Linux6.6.145Vendor (CNA)
Linux Linux9442d75429b0c556292a7454fe888d54259f5240Vendor (CNA)
Linux Linuxb54aee5652fcd7c23a0904a4623ec462c3edc70cVendor (CNA)
Linux Linuxbe87de7789a82a030a4896bc7683415ec9fa6f2bVendor (CNA)
Linux Linuxfb49099206c5c57af28a157249fa7bcb5518f99eVendor (CNA)
Linux Linuxfdd6229d2ae9914c1f25d1041db0f4f312a4fa76Vendor (CNA)
azl3 kernel 6.6.144.1-1 on Azure Linux 3.06.6.145.2-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.180-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.100-1~deb12u1 · Debian:12Package 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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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-2026-640186 days apartnet: mana: validate rx_req_idx to prevent out-of-bounds array access
    37Monitor
  • CVE-2026-4311080 days apartwifi: brcmfmac: validate bsscfg indices in IF events
    35Monitor
  • CVE-2026-4317280 days apartwifi: iwlwifi: fix 22000 series SMEM parsing
    35Monitor
  • CVE-2026-23246129 days apartwifi: mac80211: bounds-check link_id in ieee80211_ml_reconfiguration
    35Monitor
  • CVE-2026-642710 days apartInput: touchwin - reset the packet index on every complete packet
    31Monitor
  • CVE-2026-642720 days apartInput: mms114 - fix touch indexing for MMS134S and MMS136
    31Monitor

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).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • 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
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-129 · Improper Validation of Array Index

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/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 (7 more)

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

All records