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NVD / CVE Program· CNA Linux

CVE-2026-93813: btrfs: tree-checker: validate INODE_REF's namelen

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: 0.12% (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 3dc22abc21f5892406c09202fa2627196cc96967, 4cb41f07685f88ec724a375883bb0c731db8f6eb, 509d6a4d889e425f305461d8323a7b39ca6c121c; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.158.1-1.

Low priority for now. Upgrade to Linux Linux 3dc22abc21f5892406c09202fa2627196cc96967, 4cb41f07685f88ec724a375883bb0c731db8f6eb, 509d6a4d889e425f305461d8323a7b39ca6c121c; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.158.1-1 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: btrfs: tree-checker: validate INODE_REF's namelen [BUG] A crafted btrfs image can trigger the following crash: BUG: unable to handle page fault for address: ffffd1dc42884000 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page CPU: 9 UID: 0 PID: 1034 Comm: poc Not tainted 7.1.0-rc4-custom+ #383 PREEMPT(full) 46af0a92938a63be7132e0dfd71e62327c51d5c2 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022 RIP: 0010:memcpy+0xc/0x10 Call Trace: <TASK> read_extent_buffer+0xe4/0x100 [btrfs 3cf0785dd58fec8c5ff84633b772f17ce1f92a8f] btrfs_get_name+0x15e/0x1e0 [btrfs 3cf0785dd58fec8c5ff84633b772f17ce1f92a8f] reconnect_path+0x165/0x390 exportfs_decode_fh_raw+0x337/0x400 ? drop_caches_sysctl_handler+0xb0/0xb0 </TASK> ---[ end trace 0000000000000000 ]--- RIP: 0010:memcpy+0xc/0x10 Kernel panic - not syncing: Fatal exception [CAUSE] TThe crafted image has the following corrupted INODE_REF item: item 9 key (258 INODE_REF 257) itemoff 11544 itemsize 4106 index 2 namelen 4096 name: d\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000 The itemsize matches the namelen, but the namelen is 4096, way larger than normal name length limit (BTRFS_NAME_LEN, 255). Meanwhile the memory of the @name is only 255 byte sized, this will cause out-of-boundary access, and cause the above crash. [FIX] Add extra namelen verification for INODE_REF, just like what we have done in ROOT_REF checks. Now the crafted image can be rejected gracefully: BTRFS critical (device dm-2): corrupt leaf: root=5 block=30572544 slot=14 ino=259, invalid inode ref name length, has 4096 expect [1, 255] BTRFS error (device dm-2): read time tree block corruption detected on logical 30572544 mirror 2 [ Rebase, add a Link: tag, add an simple cause analyze ]

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Sep 24, 2026
Updated
Oct 3, 2026
EPSS
0.1% · 2th percentile
CWE
—

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%

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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  • No public exploit code on record
  • A fix has been released

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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?

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.

—

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

    • 2.6.37affected
    • 2ede0daf01549cecf4bb0962c46dc47382047523 and later · before 60078a3e25c09d9d8fba828b0d81bb33e449a1b2affected · git
    • 2ede0daf01549cecf4bb0962c46dc47382047523 and later · before 509d6a4d889e425f305461d8323a7b39ca6c121caffected · git
    • 2ede0daf01549cecf4bb0962c46dc47382047523 and later · before 4cb41f07685f88ec724a375883bb0c731db8f6ebaffected · git
    • 2ede0daf01549cecf4bb0962c46dc47382047523 and later · before eeddee090b834a7d4b6a8214d2e3739e64c7a338affected · git
    • 2ede0daf01549cecf4bb0962c46dc47382047523 and later · before 8f75c19892263bc0555fba922aefe103e841e86daffected · git
    • 2ede0daf01549cecf4bb0962c46dc47382047523 and later · before 3dc22abc21f5892406c09202fa2627196cc96967affected · git
    • before 2.6.37not affected · semver
    • 5.15.222 and later · up to and including 5.15.*not affected · semver
    • 6.1.189 and later · up to and including 6.1.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.190-16.1.190-1
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-93811Sep 24, 2026 · ksmbd: Fix acl.sd_buf memory leak and invalid sd_size error handling
    0Monitor
  • ← EarlierCVE-2026-93812Sep 24, 2026 · ksmbd: fix sd_ndr.data memory leak in ksmbd_vfs_set_sd_xattr
    0Monitor
  • Later →CVE-2026-93814Sep 24, 2026 · spi: core: Abort active target transfer on controller suspend
    0Monitor

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 Linux3dc22abc21f5892406c09202fa2627196cc96967Vendor (CNA)
Linux Linux4cb41f07685f88ec724a375883bb0c731db8f6ebVendor (CNA)
Linux Linux509d6a4d889e425f305461d8323a7b39ca6c121cVendor (CNA)
Linux Linux60078a3e25c09d9d8fba828b0d81bb33e449a1b2Vendor (CNA)
Linux Linux8f75c19892263bc0555fba922aefe103e841e86dVendor (CNA)
Linux Linuxeeddee090b834a7d4b6a8214d2e3739e64c7a338Vendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.06.6.158.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.1.190-1 · Debian:12Package registry (OSV)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~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.

No nightly-computed relations.

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)

—

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.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. 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