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CVE-2026-55392

NILFS utilities - Undefined Behavior and Out-of-Memory via Unvalidated s_log_block_size

6.7 MediumFix available

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to validate s_log_block_size field in NILFS2 superblock before bit-shift operations. Attackers supplying crafted NILFS2 images trigger undefined behavior through oversized shifts or out-of-memory conditions, crashing tools like nilfs-tune and dumpseg.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
None
User interaction
Active

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.15%Unchanged since Jun 23, 2026
90%50%10%1%

What each source reports

CVE List Score used 6.7

NILFS utilities - Undefined Behavior and Out-of-Memory via Unvalidated s_log_block_size

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to validate s_log_block_size field in NILFS2 superblock before bit-shift operations. Attackers supplying crafted NILFS2 images trigger undefined behavior through oversized shifts or out-of-memory conditions, crashing tools like nilfs-tune and dumpseg.

Record
CVE-2026-55392
CVSS 4.0
6.7 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness
CWE-1284
Updated
2026-11-02
EUVDEUVD-2026-37927 6.7

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to validate s_log_block_size field in NILFS2 superblock before bit-shift operations. Attackers supplying crafted NILFS2 images trigger undefined behavior through oversized shifts or out-of-memory conditions, crashing tools like nilfs-tune and dumpseg.

Record
EUVD-2026-37927
CVSS 4.0
6.7 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-f559-vgh2-9hj6 6.7

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to...

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to validate s_log_block_size field in NILFS2 superblock before bit-shift operations. Attackers supplying crafted NILFS2 images trigger undefined behavior through oversized shifts or out-of-memory conditions, crashing tools like nilfs-tune and dumpseg.

Record
GHSA-f559-vgh2-9hj6
CVSS 4.0
6.7 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness
CWE-1284
Updated
2026-11-02
NVD 6.7

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to validate s_log_block_size field in NILFS2 superblock before bit-shift operations. Attackers supplying crafted NILFS2 images trigger undefined behavior through oversized shifts or out-of-memory conditions, crashing tools like nilfs-tune and dumpseg.

Record
CVE-2026-55392
CVSS 4.0
6.7 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness
CWE-1284
Updated
2026-11-02
OSV 6.7

NILFS utilities - Undefined Behavior and Out-of-Memory via Unvalidated s_log_block_size

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to validate s_log_block_size field in NILFS2 superblock before bit-shift operations. Attackers supplying crafted NILFS2 images trigger undefined behavior through oversized shifts or out-of-memory conditions, crashing tools like nilfs-tune and dumpseg.

Record
CVE-2026-55392
CVSS 4.0
6.7 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-1284
Updated
2026-11-02
OSVDEBIAN-CVE-2026-55392 6.7

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to validate s_log_block_size field in NILFS2 superblock before bit-shift operations. Attackers supplying crafted NILFS2 images trigger undefined behavior through oversized shifts or out-of-memory conditions, crashing tools like nilfs-tune and dumpseg.

Record
DEBIAN-CVE-2026-55392
CVSS 4.0
6.7 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-02
Show 9 moreShow less
OSVOESA-2026-2795 5.5

nilfs-utils security update

Userspace utilities for creating and mounting NILFS v2 filesystems.

Security Fix(es):

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to validate s_log_block_size field in NILFS2 superblock before bit-shift operations. Attackers supplying crafted NILFS2 images trigger undefined behavior through oversized shifts or out-of-memory conditions, crashing tools like nilfs-tune and dumpseg.(CVE-2026-55392)

Record
OESA-2026-2795
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVOESA-2026-2796 5.5

nilfs-utils security update

Userspace utilities for creating and mounting NILFS v2 filesystems.

Security Fix(es):

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to validate s_log_block_size field in NILFS2 superblock before bit-shift operations. Attackers supplying crafted NILFS2 images trigger undefined behavior through oversized shifts or out-of-memory conditions, crashing tools like nilfs-tune and dumpseg.(CVE-2026-55392)

Record
OESA-2026-2796
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVOESA-2026-2797 5.5

nilfs-utils security update

Userspace utilities for creating and mounting NILFS v2 filesystems.

Security Fix(es):

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to validate s_log_block_size field in NILFS2 superblock before bit-shift operations. Attackers supplying crafted NILFS2 images trigger undefined behavior through oversized shifts or out-of-memory conditions, crashing tools like nilfs-tune and dumpseg.(CVE-2026-55392)

Record
OESA-2026-2797
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVOESA-2026-2840 5.5

nilfs-utils security update

Userspace utilities for creating and mounting NILFS v2 filesystems.

Security Fix(es):

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to validate s_log_block_size field in NILFS2 superblock before bit-shift operations. Attackers supplying crafted NILFS2 images trigger undefined behavior through oversized shifts or out-of-memory conditions, crashing tools like nilfs-tune and dumpseg.(CVE-2026-55392)

Record
OESA-2026-2840
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2026-55392 6.7

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to validate s_log_block_size field in NILFS2 superblock before bit-shift operations. Attackers supplying crafted NILFS2 images trigger undefined behavior through oversized shifts or out-of-memory conditions, crashing tools like nilfs-tune and dumpseg.

Record
UBUNTU-CVE-2026-55392
CVSS 4.0
6.7 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVAZL-90200 No score

CVE-2026-55392 affecting package nilfs-utils 2.2.11-4

NILFS utilities through 2.3.0, fixed in commit 26efb5d, nilfs_sb_is_valid() function fails to validate s_log_block_size field in NILFS2 superblock before bit-shift operations. Attackers supplying crafted NILFS2 images trigger undefined behavior through oversized shifts or out-of-memory conditions, crashing tools like nilfs-tune and dumpseg.

Record
AZL-90200
Updated
2026-11-05
OSVMGASA-2026-0280 No score

Updated nilfs-utils packages fix security vulnerability

Undefined Behavior and Out-of-Memory via Unvalidated s_log_block_size. (CVE-2026-55392)

Record
MGASA-2026-0280
Updated
2026-11-02
OSVopenSUSE-SU-2026:11094-1 No score

libnilfs3-2.3.1-1.1 on GA media

These are all security issues fixed in the libnilfs3-2.3.1-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:11094-1
Updated
2026-11-02
OSVopenSUSE-SU-2026:21183-1 No score

Security update for nilfs-utils

This update for nilfs-utils fixes the following issues:

Changes in nilfs-utils:

  • CVE-2026-55392: Fixed undefined behavior in nilfs_sb_is_valid() (bsc#1268553)
Record
openSUSE-SU-2026:21183-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
nilfs-utils
Azure Linux:3
 through 2.2.11-4 None known
nilfs-tools
Debian:12
 All versions, plus listed versions
2.2.11-12.2.11-22.2.9-1
 None known
nilfs-tools
Debian:13
 All versions, plus listed versions
2.2.11-2
 None known
nilfs-tools
Debian:14
 All versions, plus listed versions
2.2.11-2
 None known
nilfs-utils
Mageia:10
 before 2.2.11-3.1.mga10
2.2.11-3.1.mga10
nilfs-utils
Mageia:9
 before 2.2.9-1.1.mga9
2.2.9-1.1.mga9
nilfs-utils
openEuler:22.03-LTS-SP4
 before 2.2.8-2.oe2203sp4
2.2.8-2.oe2203sp4
nilfs-utils
openEuler:24.03-LTS-SP1
 before 2.2.9-2.oe2403sp1
2.2.9-2.oe2403sp1
nilfs-utils
openEuler:24.03-LTS-SP3
 before 2.2.9-2.oe2403sp3
2.2.9-2.oe2403sp3
nilfs-utils
openEuler:20.03-LTS-SP4
 before 2.2.7-7.oe2003sp4
2.2.7-7.oe2003sp4
Show 10 moreShow less
Affected packages
PackageAffectedFixed
nilfs-tools
Ubuntu:16.04:LTS
 All versions, plus listed versions
2.2.3-2
 None known
nilfs-tools
Ubuntu:18.04:LTS
 All versions, plus listed versions
2.2.6-1
 None known
nilfs-tools
Ubuntu:20.04:LTS
 All versions, plus listed versions
2.2.7-12.2.8-1
 None known
nilfs-tools
Ubuntu:22.04:LTS
 All versions, plus listed versions
2.2.8-1
 None known
nilfs-tools
Ubuntu:24.04:LTS
 All versions, plus listed versions
2.2.9-1
 None known
nilfs-tools
Ubuntu:25.10
 All versions, plus listed versions
2.2.11-2
 None known
nilfs-tools
Ubuntu:26.10
 All versions, plus listed versions
2.2.11-2build1
 None known
nilfs-tools
Ubuntu:26.04:LTS
 All versions, plus listed versions
2.2.11-22.2.11-2build1
 None known
nilfs-utils
openSUSE:Tumbleweed
 before 2.3.1-1.1
2.3.1-1.1
nilfs-utils
openSUSE:Leap 16.0
 before 2.2.9-bp160.2.1
2.2.9-bp160.2.1

History

History
RecordedChangedSources
factsOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-55392 is a medium vulnerability (CVSS 6.7) in Nilfs-dev Nilfs-utils, published June 18, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.15%, the 4th percentile. Fixed in nilfs-utils 2.2.11-3.1.mga10.

References

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