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NVD / CVE Program· CNA Linux

CVE-2025-71123: ext4: fix string copying in parse_apply_sb_mount_options()

Noroxi assessment

Priority: Monitor (action score 31/100)

  • 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: 0.17% (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 5.10.248, 5.5, 52ac96c4a2dd7bc47666000440b0602d9742e820.

Low priority for now. Upgrade to Linux Linux 5.10.248, 5.5, 52ac96c4a2dd7bc47666000440b0602d9742e820 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: ext4: fix string copying in parse_apply_sb_mount_options() strscpy_pad() can't be used to copy a non-NUL-term string into a NUL-term string of possibly bigger size. Commit 0efc5990bca5 ("string.h: Introduce memtostr() and memtostr_pad()") provides additional information in that regard. So if this happens, the following warning is observed: strnlen: detected buffer overflow: 65 byte read of buffer size 64 WARNING: CPU: 0 PID: 28655 at lib/string_helpers.c:1032 __fortify_report+0x96/0xc0 lib/string_helpers.c:1032 Modules linked in: CPU: 0 UID: 0 PID: 28655 Comm: syz-executor.3 Not tainted 6.12.54-syzkaller-00144-g5f0270f1ba00 #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:__fortify_report+0x96/0xc0 lib/string_helpers.c:1032 Call Trace: <TASK> __fortify_panic+0x1f/0x30 lib/string_helpers.c:1039 strnlen include/linux/fortify-string.h:235 [inline] sized_strscpy include/linux/fortify-string.h:309 [inline] parse_apply_sb_mount_options fs/ext4/super.c:2504 [inline] __ext4_fill_super fs/ext4/super.c:5261 [inline] ext4_fill_super+0x3c35/0xad00 fs/ext4/super.c:5706 get_tree_bdev_flags+0x387/0x620 fs/super.c:1636 vfs_get_tree+0x93/0x380 fs/super.c:1814 do_new_mount fs/namespace.c:3553 [inline] path_mount+0x6ae/0x1f70 fs/namespace.c:3880 do_mount fs/namespace.c:3893 [inline] __do_sys_mount fs/namespace.c:4103 [inline] __se_sys_mount fs/namespace.c:4080 [inline] __x64_sys_mount+0x280/0x300 fs/namespace.c:4080 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x64/0x140 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x76/0x7e Since userspace is expected to provide s_mount_opts field to be at most 63 characters long with the ending byte being NUL-term, use a 64-byte buffer which matches the size of s_mount_opts, so that strscpy_pad() does its job properly. Return with error if the user still managed to provide a non-NUL-term string here. Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Jan 14, 2026
Updated
Oct 15, 2026
EPSS
0.1% · 6th percentile
CWE
—

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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  • 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 kernel5.4.301 and later · before 5.5
  • linux linux kernel5.10.246 and later · before 5.10.248
  • linux linux kernel6.1.158 and later · before 6.1.160
  • linux linux kernel6.6.114 and later · before 6.6.120
  • linux linux kernel6.12.54 and later · before 6.12.64
  • linux linux kernel6.17.4 and later · before 6.18
  • linux linux kernel6.18.1 and later · before 6.18.3
  • linux linux kernel6.18
  • linux linux kernel6.19

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

    • 7bf46ff83a0ef11836e38ebd72cdc5107209342d, a6e94557cd05adc82fae0400f6e17745563e5412, 6.18affected
    • b2bac84fde28fb6a88817b8b761abda17a1d300b and later · before 52ac96c4a2dd7bc47666000440b0602d9742e820affected · git
    • e651294218d2684302ee5ed95ccf381646f3e5b4 and later · before 6e37143560e37869d51b7d9e0ac61fc48895f8a0affected · git
    • 01829af7656b56d83682b3491265d583d502e502 and later · before 902ca2356f1e3ec5355c5808ad5d3f9d0095b0ccaffected · git
    • 2a0cf438320cdb783e0378570744c0ef0d83e934 and later · before db9ee13fab0267eccf6544ee35b16c9522db9aacaffected · git
    • 8ecb790ea8c3fc69e77bace57f14cf0d7c177bd8 and later · before 5bbacbbf1ca4419861dca3c6b82707c10e9c021caffected · git
    • 8ecb790ea8c3fc69e77bace57f14cf0d7c177bd8 and later · before ee5a977b4e771cc181f39d504426dbd31ed701ccaffected · git
    • 5.10.246 and later · before 5.10.248affected · semver
    • 6.1.158 and later · before 6.1.160affected · semver
    • 6.6.114 and later · before 6.6.120affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.162-16.1.162-1
Debian:13linuxbefore 6.12.69-16.12.69-1
Debian:14linuxbefore 6.18.3-16.18.3-1

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-2025-71120Jan 14, 2026 · SUNRPC: svcauth_gss: avoid NULL deref on zero length gss_token in gss_read_proxy_verf
    22Monitor
  • ← EarlierCVE-2025-71122Jan 14, 2026 · iommufd/selftest: Check for overflow in IOMMU_TEST_OP_ADD_RESERVED
    31Monitor
  • Later →CVE-2025-71125Jan 14, 2026 · tracing: Do not register unsupported perf events
    22Monitor

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 Linux5.10.248Vendor (CNA)
Linux Linux5.5Vendor (CNA)
Linux Linux52ac96c4a2dd7bc47666000440b0602d9742e820Vendor (CNA)
Linux Linux5bbacbbf1ca4419861dca3c6b82707c10e9c021cVendor (CNA)
Linux Linux6.1.160Vendor (CNA)
Linux Linux6.12.64Vendor (CNA)
Linux Linux6.18Vendor (CNA)
Linux Linux6.6.120Vendor (CNA)
Linux Linux6e37143560e37869d51b7d9e0ac61fc48895f8a0Vendor (CNA)
Linux Linux902ca2356f1e3ec5355c5808ad5d3f9d0095b0ccVendor (CNA)
Linux Linuxdb9ee13fab0267eccf6544ee35b16c9522db9aacVendor (CNA)
Linux Linuxee5a977b4e771cc181f39d504426dbd31ed701ccVendor (CNA)
debian:linux6.1.162-1 · 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.

No history yet (it accumulates with the daily EPSS job).

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).

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
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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

Change log

  1. 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