NVD / CVE Program· CNA Linux

CVE-2022-49834: nilfs2: fix use-after-free bug of ns_writer on remount

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: 0.22% (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 39a3ed68270b079c6b874d4e4727a512b9b4882c, 4feedde5486c07ea79787839153a71ca71329c7d, 8cccf05fe857a18ee26e20d11a8455a73ffd4efd.

Low priority for now. Upgrade to Linux Linux 39a3ed68270b079c6b874d4e4727a512b9b4882c, 4feedde5486c07ea79787839153a71ca71329c7d, 8cccf05fe857a18ee26e20d11a8455a73ffd4efd 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 use-after-free bug of ns_writer on remount If a nilfs2 filesystem is downgraded to read-only due to metadata corruption on disk and is remounted read/write, or if emergency read-only remount is performed, detaching a log writer and synchronizing the filesystem can be done at the same time. In these cases, use-after-free of the log writer (hereinafter nilfs->ns_writer) can happen as shown in the scenario below: Task1 Task2 -------------------------------- ------------------------------ nilfs_construct_segment nilfs_segctor_sync init_wait init_waitqueue_entry add_wait_queue schedule nilfs_remount (R/W remount case) nilfs_attach_log_writer nilfs_detach_log_writer nilfs_segctor_destroy kfree finish_wait _raw_spin_lock_irqsave __raw_spin_lock_irqsave do_raw_spin_lock debug_spin_lock_before <-- use-after-free While Task1 is sleeping, nilfs->ns_writer is freed by Task2. After Task1 waked up, Task1 accesses nilfs->ns_writer which is already freed. This scenario diagram is based on the Shigeru Yoshida's post [1]. This patch fixes the issue by not detaching nilfs->ns_writer on remount so that this UAF race doesn't happen. Along with this change, this patch also inserts a few necessary read-only checks with superblock instance where only the ns_writer pointer was used to check if the filesystem is read-only.

HighCVSS 7.8 · v3.1—No exploit Fix available

Memory safety

BDU:2026-01509

Published: May 1, 2025
Updated: Aug 5, 2026
EPSS: 0.2% · 12th percentile
CWE: CWE-416

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 31 / 40 · 7.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.2%

CNA vs NVD score

NVD: 7.8
CNA · Linux: 7.8; agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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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Noroxi analysis

What does it mean in your environment?

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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.

Vendor	Product	CPE
linux	linux kernel	cpe:2.3:o:linux:linux_kernel

Affected versions

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

linux linux kernelbefore 4.9.334
linux linux kernel4.10 and later · before 4.14.300
linux linux kernel4.15 and later · before 4.19.267
linux linux kernel4.20 and later · before 5.4.225
linux linux kernel5.5 and later · before 5.10.155
linux linux kernel5.11 and later · before 5.15.79
linux linux kernel5.16 and later · before 6.0.9
linux linux kernel6.1

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
- 2.6.34affected
- fe5f171bb272946ce5fbf843ce2f8467d0d41b9a and later · before b2fbf10040216ef5ee270773755fc2f5da65b749affected · git
- fe5f171bb272946ce5fbf843ce2f8467d0d41b9a and later · before 39a3ed68270b079c6b874d4e4727a512b9b4882caffected · git
- fe5f171bb272946ce5fbf843ce2f8467d0d41b9a and later · before b4736ab5542112fe0a40f140a0a0b072954f34daaffected · git
- fe5f171bb272946ce5fbf843ce2f8467d0d41b9a and later · before 9b162e81045266a2d5b44df9dffdf05c54de9ccaaffected · git
- fe5f171bb272946ce5fbf843ce2f8467d0d41b9a and later · before 4feedde5486c07ea79787839153a71ca71329c7daffected · git
- fe5f171bb272946ce5fbf843ce2f8467d0d41b9a and later · before afbd1188382a75f6cfe22c0b68533f7f9664f182affected · git
- fe5f171bb272946ce5fbf843ce2f8467d0d41b9a and later · before b152300d5a1ba4258dacf9916bff20e6a8c7603baffected · git
- fe5f171bb272946ce5fbf843ce2f8467d0d41b9a and later · before 8cccf05fe857a18ee26e20d11a8455a73ffd4efdaffected · git
- before 2.6.34not affected · semver

Package-level exposure

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

Ecosystem	Package	Affected range	Fix
Debian:12	linux	before 6.0.10-1	6.0.10-1

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
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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-2022-49832May 1, 2025 · pinctrl: devicetree: fix null pointer dereferencing in pinctrl_dt_to_map
22Monitor
← EarlierCVE-2022-49833May 1, 2025 · btrfs: zoned: clone zoned device info when cloning a device
22Monitor
Later →CVE-2022-49835May 1, 2025 · ALSA: hda: fix potential memleak in 'add_widget_node'
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 / package	Fixed version	Source
Linux Linux	39a3ed68270b079c6b874d4e4727a512b9b4882c	Vendor (CNA)
Linux Linux	4feedde5486c07ea79787839153a71ca71329c7d	Vendor (CNA)
Linux Linux	8cccf05fe857a18ee26e20d11a8455a73ffd4efd	Vendor (CNA)
Linux Linux	9b162e81045266a2d5b44df9dffdf05c54de9cca	Vendor (CNA)
Linux Linux	afbd1188382a75f6cfe22c0b68533f7f9664f182	Vendor (CNA)
Linux Linux	b152300d5a1ba4258dacf9916bff20e6a8c7603b	Vendor (CNA)
Linux Linux	b2fbf10040216ef5ee270773755fc2f5da65b749	Vendor (CNA)
Linux Linux	b4736ab5542112fe0a40f140a0a0b072954f34da	Vendor (CNA)
debian:linux	6.0.10-1 · Debian:12	Package 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)

CWE-416 · Use After Free

CVSS vector

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

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

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

Fix✗ → ✓Sep 28, 2026, 10:08 PM UTC

For records you follow, these changes also arrive as notifications. →

References

git.kernel.org/stable/c/39a3ed68270b079c6b874d4e4727a512b9b4882c

Show all references (7 more)

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

All records