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CVE-2026-53391· NVD / CVE Program· CNA Linux

NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr

Noroxi assessment

Priority: Monitor (action score 30/100)

  • 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: 0.51% (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 012d37a568bfbb2c9686f03ade75560bc7139956, 30aae62e50b4e074a90a9a5e15246548fbdc1182, 41fe0f7b84f0cb822ae10ab08592996a592b2a25; azl3 kernel 6.6.143.1-1 on Azure Linux 3.0 6.6.150.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 012d37a568bfbb2c9686f03ade75560bc7139956, 30aae62e50b4e074a90a9a5e15246548fbdc1182, 41fe0f7b84f0cb822ae10ab08592996a592b2a25; azl3 kernel 6.6.143.1-1 on Azure Linux 3.0 6.6.150.1-1 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: NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr nfs4_decode_mp_ds_addr() decodes the r_netid and r_addr opaques of a netaddr4 from a GETDEVICEINFO multipath-DS body, then immediately calls strrchr(buf, '.') to locate the port separator. Both decodes use xdr_stream_decode_string_dup(), and the current code checks only "nlen < 0" / "rlen < 0" before dereferencing the returned string. When the on-wire opaque has length zero, xdr_stream_decode_opaque_inline() returns 0 and xdr_stream_decode_string_dup() falls through to its "*str = NULL; return ret" tail, leaving buf NULL with a return value of 0. The "< 0" check does not catch this, and the next line is strrchr(NULL, '.'), a kernel NULL pointer dereference reachable from any pNFS-flexfile client mounted against a malicious or compromised metadata server. Reject the zero-length cases explicitly so the decoder fails with -EBADMSG (treated as a malformed GETDEVICEINFO body) instead of panicking the client.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Jul 19, 2026
Updated
Oct 19, 2026
EPSS
0.5% · 43th percentile

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.5
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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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 kernel4.0 and later · before 5.15.211
  • linux linux kernel5.16 and later · before 6.1.177
  • linux linux kernel6.2 and later · before 6.6.144
  • linux linux kernel6.7 and later · before 6.12.95
  • linux linux kernel6.13 and later · before 6.18.38
  • linux linux kernel6.19 and later · before 7.1.3

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

    • 4.0affected
    • 6b7f3cf96364eaf597940cb5c68a682894829915 and later · before 76b94cbd32aacf36a641956385a852635c6802b9affected · git
    • 6b7f3cf96364eaf597940cb5c68a682894829915 and later · before c8e4e0c701d0192a2efb6df059c0f9e19678c23daffected · git
    • 6b7f3cf96364eaf597940cb5c68a682894829915 and later · before 6c344fff2feff9d4d716d8e4ad40e9b5040ee5eaaffected · git
    • 6b7f3cf96364eaf597940cb5c68a682894829915 and later · before 427ab81a811dab4bca9d19f82eec5847ae42646eaffected · git
    • 6b7f3cf96364eaf597940cb5c68a682894829915 and later · before 012d37a568bfbb2c9686f03ade75560bc7139956affected · git
    • 6b7f3cf96364eaf597940cb5c68a682894829915 and later · before 30aae62e50b4e074a90a9a5e15246548fbdc1182affected · git
    • 6b7f3cf96364eaf597940cb5c68a682894829915 and later · before 41fe0f7b84f0cb822ae10ab08592996a592b2a25affected · git
    • before 4.0not affected · semver
    • 5.15.211 and later · up to and including 5.15.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • 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
  • CVE-2016-5195Race condition in mm/gup.c in the Linux kernel 2.x through 4.x before 4.8.3 allows local users to gain privileges by leveraging incorrect haKEV
    83Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-53384Jul 19, 2026 · serial: 8250_dw: unregister 8250 port if clk_notifier_register() fails
    39Monitor
  • ← EarlierCVE-2026-53388Jul 19, 2026 · fuse: re-lock request before replacing page cache folio
    31Monitor
  • Later →CVE-2026-53392Jul 19, 2026 · NFSv4/flexfiles: reject zero filehandle version count
    30Monitor

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 Linux012d37a568bfbb2c9686f03ade75560bc7139956Vendor (CNA)
Linux Linux30aae62e50b4e074a90a9a5e15246548fbdc1182Vendor (CNA)
Linux Linux41fe0f7b84f0cb822ae10ab08592996a592b2a25Vendor (CNA)
Linux Linux427ab81a811dab4bca9d19f82eec5847ae42646eVendor (CNA)
Linux Linux6c344fff2feff9d4d716d8e4ad40e9b5040ee5eaVendor (CNA)
Linux Linux76b94cbd32aacf36a641956385a852635c6802b9Vendor (CNA)
Linux Linuxc8e4e0c701d0192a2efb6df059c0f9e19678c23dVendor (CNA)
azl3 kernel 6.6.143.1-1 on Azure Linux 3.06.6.150.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:kernel6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-core6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-core6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-core6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:kernel-64k-devel-matched6.12.0-211.50.1.el10_2 · AlmaLinux:10Package registry (OSV)
debian:linux6.1.177-1 · Debian:12Package registry (OSV)
opensuse:kernel-source7.1.4-1.1 · openSUSE:TumbleweedPackage registry (OSV)
red hat:kernel-64k-debug-debuginfo0:6.12.0-211.50.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel0:6.12.0-211.50.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debug-devel-matched0:6.12.0-211.50.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-debuginfo0:6.12.0-211.50.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel0:6.12.0-211.50.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-64k-devel-matched0:6.12.0-211.50.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-debuginfo0:6.12.0-211.50.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:kernel-debug-devel0:6.12.0-211.50.1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)

+6

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
none
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
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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 (6 more)

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

All records