CVE Intelligence
Medium Memory corruption

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

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 Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Linux

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.2% (30-day exploitation probability)+1
  • Technical severity (medium)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.17%
ahead of 5% of scored CVEs · Oct 15, 2026
Affects
Linux
Linux and 1 more
CVSS base
5.5
Medium · 1 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Linux Linux, Linux Linux Kernel).
  2. Apply the fixed version or the patch documented under Remediation.
  3. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Linux Linux ≥ e897be17a441fa637cd166fc3de1445131e57692 and < 97fb7afec404912d967a7d4715f37742666b3084version 5.18≥ 5.17.10 and < 5.18≥ 5.4.196 and < 5.5≥ 4.19.245 and < 4.20≥ 4.14.296 and < 4.15≥ 5.15.42 and < 5.15.209≥ 5.10.118 and < 5.10.258
and 12 more version 1829b24a36ca12ca95b96d5478faeff40c17f2b6version 307d021b1a7f33048b624f7aaeaa75e3eae571f1version 605babb979c213737618b1c837e89624e5ab11fdversion 6c3da8c0a35bbafe359d9166269d5590f29664de≥ e897be17a441fa637cd166fc3de1445131e57692 and < 4a4e0328edd9e9755843787d28f16dd4165f8b48≥ e897be17a441fa637cd166fc3de1445131e57692 and < 41de342278ae025c99cc8d33648773f05e306cf1≥ e897be17a441fa637cd166fc3de1445131e57692 and < c36e206f302f1ddefed92d09ecbba070e1ae079e≥ e897be17a441fa637cd166fc3de1445131e57692 and < 449ec5fc99f45974525ba9eea16b6670c45cd363≥ e897be17a441fa637cd166fc3de1445131e57692 and < 7318e3549518ce8f14776a489d86488d80d7e2c8≥ e897be17a441fa637cd166fc3de1445131e57692 and < 7902b1df1520a0880bcda7a3704cfacd17905a83≥ d05cc5395e36711edad8bdef6945f138d8a7097b and < 837c7a59fb58f81b0db33848357f6a5d0d1250ad≥ d626fcdabea2258be395a775bdbe09270e9bf73d and < 6637bbcfb59df5b732a79e5ab1a74886a0b93d59
Vulnerable CVE Program (cve.org) e CISA ADP
Linux Linux Kernel < 6.6.136≥ 7.0 and < 7.0.1≥ 6.19 and < 6.19.14≥ 6.13 and < 6.18.24≥ 6.7 and < 6.12.83 Vulnerable NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
5.5 CVSS 3.1 Medium 1.8 3.6 nvd@nist.gov via NIST National Vulnerability Database
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-476 · NULL Pointer Dereference

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 0.17%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
endpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · linux/linux
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • Fix documented
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVSS changed · 5.5
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Modified
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVE published
    Apr 24, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

9 on the record

Elsewhere on this site

Linux
every CVE for this vendor
Memory corruption
same class
CWE-476
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-99999 ipv4: validate checksum_start before completing checksum 20h
  • CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 20h
  • CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 1d
  • CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 1d
  • CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 1d
  • CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No CISA SSVC assessment.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-31577 is "nilfs2: fix NULL i_assoc_inode dereference in nilfs_mdt_save_to_shadow_map", rated Medium. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.5 describes technical severity. EPSS 0.17% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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