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NVD / CVE Program· CNA Linux

CVE-2026-89649: ceph: bound xattr value length in __build_xattrs()

Noroxi assessment

Priority: Monitor (action score 36/100)

  • 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: 0.67% (FIRST EPSS); higher than 52.1% of all records.
  • 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 01e3f19c301d492e12f16b3b463ac14d7cf3ebe7, 1dd356310b1660215f9a3626580bf8b363ef981e, 38be2f3c41ecaba58bb92dc16603e09ba9fd64f1; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 6.6.157.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 01e3f19c301d492e12f16b3b463ac14d7cf3ebe7, 1dd356310b1660215f9a3626580bf8b363ef981e, 38be2f3c41ecaba58bb92dc16603e09ba9fd64f1; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 6.6.157.1-1 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: ceph: bound xattr value length in __build_xattrs() __build_xattrs() decodes the MDS-supplied xattr blob one attribute at a time. For each attribute it reads a 32-bit name length, advances past the name bytes, reads a 32-bit value length, records the value pointer, and advances past the value bytes. The two length fields are read with ceph_decode_32_safe(), but the value bytes themselves are advanced over with a bare "p += len" and no ceph_decode_need() check that "len" bytes remain in the blob. For every attribute except the last, the next iteration's ceph_decode_32_safe() on the following name length implicitly verifies that the previous value did not run past the blob end. The final attribute has no successor, so its decoded value length is never checked against the blob bounds. A malicious or compromised metadata server can set the last attribute's value length larger than the bytes actually present in the blob. The blob is a dedicated kvmalloc() allocation sized to the wire length (ceph_buffer_new() in ceph_fill_inode()). __set_xattr() records the oversized length in xattr->val_len verbatim, and a later getxattr(2) runs memcpy(value, xattr->val, xattr->val_len) into a user-supplied buffer, copying bytes past the end of the allocation back to user space. Impact: a malicious metadata server discloses adjacent kernel heap bytes to a local user via getxattr(2) on a CephFS file. Add the missing ceph_decode_need() so an out-of-bounds value length on the final attribute fails the decode and returns -EIO instead of being stored.

CriticalCVSS 9.1 · v3.1—No exploit Fix available
Published
Sep 11, 2026
Updated
Oct 19, 2026
EPSS
0.6% · 52th percentile
CWE
—

Report tools

JSON

Action score

36

Monitor

Low priority for now.

CVSS
36 / 40 · 9.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.6%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.1
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.

Get told when this record changes

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

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • 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

    • 2.6.34affected
    • 355da1eb7a1f91c276b991764e951bbcd8047599 and later · before 848b80ca6b410f350d08b8ac19a00ef88223f2eaaffected · git
    • 355da1eb7a1f91c276b991764e951bbcd8047599 and later · before 01e3f19c301d492e12f16b3b463ac14d7cf3ebe7affected · git
    • 355da1eb7a1f91c276b991764e951bbcd8047599 and later · before cb0cd79ae80476d1bc06bd9678484b6736f19588affected · git
    • 355da1eb7a1f91c276b991764e951bbcd8047599 and later · before 61f085cb8976c9cebc90e1a8933e4cc1ad8b0fceaffected · git
    • 355da1eb7a1f91c276b991764e951bbcd8047599 and later · before 38be2f3c41ecaba58bb92dc16603e09ba9fd64f1affected · git
    • 355da1eb7a1f91c276b991764e951bbcd8047599 and later · before 1dd356310b1660215f9a3626580bf8b363ef981eaffected · git
    • 355da1eb7a1f91c276b991764e951bbcd8047599 and later · before b12b3320c81fd72ab36388fb2445fec9c3038f10affected · git
    • 355da1eb7a1f91c276b991764e951bbcd8047599 and later · before 68d541754d6cd3bb98d1fd8314f57e5eb533557daffected · git
    • before 2.6.34not 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-2026-89647Sep 11, 2026 · ceph: do not repeat ceph_trim_dentries() if no progress possible
    30Monitor
  • ← EarlierCVE-2026-89648Sep 11, 2026 · ceph: cap delegated inode count in ceph_parse_deleg_inos()
    30Monitor
  • Later →CVE-2026-89650Sep 11, 2026 · ceph: bound num_export_targets array for mds info v2/v3
    36Monitor

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 Linux01e3f19c301d492e12f16b3b463ac14d7cf3ebe7Vendor (CNA)
Linux Linux1dd356310b1660215f9a3626580bf8b363ef981eVendor (CNA)
Linux Linux38be2f3c41ecaba58bb92dc16603e09ba9fd64f1Vendor (CNA)
Linux Linux61f085cb8976c9cebc90e1a8933e4cc1ad8b0fceVendor (CNA)
Linux Linux68d541754d6cd3bb98d1fd8314f57e5eb533557dVendor (CNA)
Linux Linux848b80ca6b410f350d08b8ac19a00ef88223f2eaVendor (CNA)
Linux Linuxb12b3320c81fd72ab36388fb2445fec9c3038f10Vendor (CNA)
Linux Linuxcb0cd79ae80476d1bc06bd9678484b6736f19588Vendor (CNA)
azl3 kernel 6.6.150.1-1 on Azure Linux 3.0—Microsoft (MSRC)
azl3 kernel 6.6.152.1-1 on Azure Linux 3.06.6.157.1-1 · 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).

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
none
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
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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