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NVD / CVE Program· CNA Linux

CVE-2026-31577: nilfs2: fix NULL i_assoc_inode dereference in nilfs_mdt_save_to_shadow_map

MediumCVSS 5.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 22/100)

  • 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 4.15, 4.20, 41de342278ae025c99cc8d33648773f05e306cf1; azl3 kernel 6.6.134.1-2 on Azure Linux 3.0 6.6.137.1-1; cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0 Release Notes.

Low priority for now. Upgrade to Linux Linux 4.15, 4.20, 41de342278ae025c99cc8d33648773f05e306cf1; azl3 kernel 6.6.134.1-2 on Azure Linux 3.0 6.6.137.1-1; cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0 Release Notes 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: nilfs2: fix NULL i_assoc_inode dereference in nilfs_mdt_save_to_shadow_map The DAT inode's btree node cache (i_assoc_inode) is initialized lazily during btree operations. However, nilfs_mdt_save_to_shadow_map() assumes i_assoc_inode is already initialized when copying dirty pages to the shadow map during GC. If NILFS_IOCTL_CLEAN_SEGMENTS is called immediately after mount before any btree operation has occurred on the DAT inode, i_assoc_inode is NULL leading to a general protection fault. Fix this by calling nilfs_attach_btree_node_cache() on the DAT inode in nilfs_dat_read() at mount time, ensuring i_assoc_inode is always initialized before any GC operation can use it.

Published
Apr 24, 2026
Updated
Nov 11, 2026
EPSS
0.1% · 2th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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

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  • when exploit code appears or is weaponized
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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

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

    • 6c3da8c0a35bbafe359d9166269d5590f29664de, 605babb979c213737618b1c837e89624e5ab11fd, 307d021b1a7f33048b624f7aaeaa75e3eae571f1, 1829b24a36ca12ca95b96d5478faeff40c17f2b6, 5.18affected
    • d626fcdabea2258be395a775bdbe09270e9bf73d and later · before 6637bbcfb59df5b732a79e5ab1a74886a0b93d59affected · git
    • d05cc5395e36711edad8bdef6945f138d8a7097b and later · before 837c7a59fb58f81b0db33848357f6a5d0d1250adaffected · git
    • e897be17a441fa637cd166fc3de1445131e57692 and later · before 7902b1df1520a0880bcda7a3704cfacd17905a83affected · git
    • e897be17a441fa637cd166fc3de1445131e57692 and later · before 7318e3549518ce8f14776a489d86488d80d7e2c8affected · git
    • e897be17a441fa637cd166fc3de1445131e57692 and later · before 449ec5fc99f45974525ba9eea16b6670c45cd363affected · git
    • e897be17a441fa637cd166fc3de1445131e57692 and later · before c36e206f302f1ddefed92d09ecbba070e1ae079eaffected · git
    • e897be17a441fa637cd166fc3de1445131e57692 and later · before 41de342278ae025c99cc8d33648773f05e306cf1affected · git
    • e897be17a441fa637cd166fc3de1445131e57692 and later · before 97fb7afec404912d967a7d4715f37742666b3084affected · git
    • e897be17a441fa637cd166fc3de1445131e57692 and later · before 4a4e0328edd9e9755843787d28f16dd4165f8b48affected · git
Affected versions · NVD (5)

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

  • linux linux kernelbefore 6.6.136
  • linux linux kernel6.7 and later · before 6.12.83
  • linux linux kernel6.13 and later · before 6.18.24
  • linux linux kernel6.19 and later · before 6.19.14
  • linux linux kernel7.0 and later · before 7.0.1

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.176-16.1.176-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.19.14-16.19.14-1
openSUSE:Tumbleweedkernel-sourcebefore 7.0.3-1.17.0.3-1.1

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-2026-31575Apr 24, 2026 · mm/userfaultfd: fix hugetlb fault mutex hash calculation
    22Monitor
  • ← EarlierCVE-2026-31576Apr 24, 2026 · media: hackrf: fix to not free memory after the device is registered in hackrf_probe()
    31Monitor
  • Later →CVE-2026-31578Apr 24, 2026 · media: as102: fix to not free memory after the device is registered in as102_usb_probe()
    31Monitor

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 Linux4.15Vendor (CNA)
Linux Linux4.20Vendor (CNA)
Linux Linux41de342278ae025c99cc8d33648773f05e306cf1Vendor (CNA)
Linux Linux449ec5fc99f45974525ba9eea16b6670c45cd363Vendor (CNA)
Linux Linux4a4e0328edd9e9755843787d28f16dd4165f8b48Vendor (CNA)
Linux Linux5.10.258Vendor (CNA)
Linux Linux5.15.209Vendor (CNA)
Linux Linux5.18Vendor (CNA)
Linux Linux5.5Vendor (CNA)
Linux Linux6637bbcfb59df5b732a79e5ab1a74886a0b93d59Vendor (CNA)
Linux Linux7318e3549518ce8f14776a489d86488d80d7e2c8Vendor (CNA)
Linux Linux7902b1df1520a0880bcda7a3704cfacd17905a83Vendor (CNA)
Linux Linux837c7a59fb58f81b0db33848357f6a5d0d1250adVendor (CNA)
Linux Linux97fb7afec404912d967a7d4715f37742666b3084Vendor (CNA)
Linux Linuxc36e206f302f1ddefed92d09ecbba070e1ae079eVendor (CNA)
azl3 kernel 6.6.134.1-2 on Azure Linux 3.06.6.137.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.202.1-1 on CBL-Mariner 2.0Release NotesMicrosoft (MSRC)
debian:linux6.1.176-1 · Debian:12Package registry (OSV)
opensuse:kernel-source7.0.3-1.1 · openSUSE:TumbleweedPackage 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.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

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
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
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:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

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.

References

Show all references (8 more)

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

All records