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NVD / CVE Program· CNA Linux

CVE-2025-21846: acct: perform last write from workqueue

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: 0.25% (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 56d5f3eba3f5de0efdd556de4ef381e109b973a9, 5a59ced8ffc71973d42c82484a719c8f6ac8f7f7, 5c928e14a2ccd99462f2351ead627b58075bb736; azl3 kernel 6.6.78.1-3 on Azure Linux 3.0 6.6.82.1-1; azl3 kernel 6.6.82.1-1 on Azure Linux 3.0 6.6.82.1-1.

Low priority for now. Upgrade to Linux Linux 56d5f3eba3f5de0efdd556de4ef381e109b973a9, 5a59ced8ffc71973d42c82484a719c8f6ac8f7f7, 5c928e14a2ccd99462f2351ead627b58075bb736; azl3 kernel 6.6.78.1-3 on Azure Linux 3.0 6.6.82.1-1; azl3 kernel 6.6.82.1-1 on Azure Linux 3.0 6.6.82.1-1 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: acct: perform last write from workqueue In [1] it was reported that the acct(2) system call can be used to trigger NULL deref in cases where it is set to write to a file that triggers an internal lookup. This can e.g., happen when pointing acc(2) to /sys/power/resume. At the point the where the write to this file happens the calling task has already exited and called exit_fs(). A lookup will thus trigger a NULL-deref when accessing current->fs. Reorganize the code so that the the final write happens from the workqueue but with the caller's credentials. This preserves the (strange) permission model and has almost no regression risk. This api should stop to exist though.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Mar 12, 2025
Updated
Oct 15, 2026
EPSS
0.2% · 16th 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 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
5.5
CNA · Linux
5.5
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

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2025-21846

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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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 kernel2.6.12 and later · before 6.1.130
  • linux linux kernel6.2 and later · before 6.6.80
  • linux linux kernel6.7 and later · before 6.12.17
  • linux linux kernel6.13 and later · before 6.13.5
  • linux linux kernel6.14

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

    • 2.6.12affected
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 8acbf4a88c6a98c8ed00afd1a7d1abcca9b4735eaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before b03782ae707cc45e65242c7cddd8e28f1c22cde5affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 5d5b936cfa4b0d5670ca7420ef165a074bc008ebaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 5ee8da9bea70dda492d61f075658939af33d8410affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 5c928e14a2ccd99462f2351ead627b58075bb736affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 5a59ced8ffc71973d42c82484a719c8f6ac8f7f7affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before a8136afca090412a36429cb6c2543c714d9c0f84affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 56d5f3eba3f5de0efdd556de4ef381e109b973a9affected · git
    • before 2.6.12not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.133-16.1.133-1
Debian:13linuxbefore 6.12.17-16.12.17-1

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-2025-21866Mar 12, 2025 · powerpc/code-patching: Fix KASAN hit by not flagging text patching area as VM_ALLOC
    22Monitor
  • ← EarlierCVE-2025-21844Mar 12, 2025 · smb: client: Add check for next_buffer in receive_encrypted_standard()
    22Monitor
  • Later →CVE-2025-21853Mar 12, 2025 · bpf: avoid holding freeze_mutex during mmap operation
    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 Linux56d5f3eba3f5de0efdd556de4ef381e109b973a9Vendor (CNA)
Linux Linux5a59ced8ffc71973d42c82484a719c8f6ac8f7f7Vendor (CNA)
Linux Linux5c928e14a2ccd99462f2351ead627b58075bb736Vendor (CNA)
Linux Linux5d5b936cfa4b0d5670ca7420ef165a074bc008ebVendor (CNA)
Linux Linux5ee8da9bea70dda492d61f075658939af33d8410Vendor (CNA)
Linux Linux8acbf4a88c6a98c8ed00afd1a7d1abcca9b4735eVendor (CNA)
Linux Linuxa8136afca090412a36429cb6c2543c714d9c0f84Vendor (CNA)
Linux Linuxb03782ae707cc45e65242c7cddd8e28f1c22cde5Vendor (CNA)
azl3 kernel 6.6.78.1-3 on Azure Linux 3.06.6.82.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 kernel 6.6.82.1-1 on Azure Linux 3.06.6.82.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.179.1-1 on CBL Mariner 2.05.15.179.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.182.1-1 on CBL Mariner 2.0CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.182.1-1 on CBL-Mariner 2.05.15.179.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.133-1 · 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
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.

Change log

  1. Fix✗ → ✓

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

References

Show all references (13 more)

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

All records