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NVD / CVE Program· CNA Linux

CVE-2025-21646: afs: Fix the maximum cell name length

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: 0.45% (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 7673030efe0f8ca1056d3849d61784c6caa052af, 7922b1f058fe24a93730511dd0ae2e1630920096, 7cb3e77e9b4e6ffa325a5559393d3283c9af3d01.
  • Severity is disputed: the assigning authority (CNA) scores it 7.5, NVD 5.5.

Low priority for now. Upgrade to Linux Linux 7673030efe0f8ca1056d3849d61784c6caa052af, 7922b1f058fe24a93730511dd0ae2e1630920096, 7cb3e77e9b4e6ffa325a5559393d3283c9af3d01 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: afs: Fix the maximum cell name length The kafs filesystem limits the maximum length of a cell to 256 bytes, but a problem occurs if someone actually does that: kafs tries to create a directory under /proc/net/afs/ with the name of the cell, but that fails with a warning: WARNING: CPU: 0 PID: 9 at fs/proc/generic.c:405 because procfs limits the maximum filename length to 255. However, the DNS limits the maximum lookup length and, by extension, the maximum cell name, to 255 less two (length count and trailing NUL). Fix this by limiting the maximum acceptable cellname length to 253. This also allows us to be sure we can create the "/afs/.<cell>/" mountpoint too. Further, split the YFS VL record cell name maximum to be the 256 allowed by the protocol and ignore the record retrieved by YFSVL.GetCellName if it exceeds 253.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Jan 19, 2025
Updated
Aug 5, 2026
EPSS
0.4% · 39th percentile
CWE
—

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 · 0.4%

CNA vs NVD score

NVD
5.5
CNA · Linux
7.5
2.0 point gap

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

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.

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When you'll hear from us

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  • 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 kernel5.8 and later · before 5.10.234
  • linux linux kernel5.11 and later · before 5.15.177
  • linux linux kernel5.16 and later · before 6.1.125
  • linux linux kernel6.2 and later · before 6.6.72
  • linux linux kernel6.7 and later · before 6.12.10
  • linux linux kernel6.13

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

    • 5.8affected
    • c3e9f888263bb4df11cbd623ceced02081cb2f9f and later · before 9340385468d056bb700b8f28df236b81fc86a079affected · git
    • c3e9f888263bb4df11cbd623ceced02081cb2f9f and later · before 7cb3e77e9b4e6ffa325a5559393d3283c9af3d01affected · git
    • c3e9f888263bb4df11cbd623ceced02081cb2f9f and later · before aabe47cf5ac5e1db2ae0635f189d836f67024904affected · git
    • c3e9f888263bb4df11cbd623ceced02081cb2f9f and later · before 7673030efe0f8ca1056d3849d61784c6caa052afaffected · git
    • c3e9f888263bb4df11cbd623ceced02081cb2f9f and later · before 7922b1f058fe24a93730511dd0ae2e1630920096affected · git
    • c3e9f888263bb4df11cbd623ceced02081cb2f9f and later · before 8fd56ad6e7c90ac2bddb0741c6b248c8c5d56ac8affected · git
    • before 5.8not affected · semver
    • 5.10.234 and later · up to and including 5.10.*not affected · semver
    • 5.15.177 and later · up to and including 5.15.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.128-16.1.128-1
Debian:13linuxbefore 6.12.10-16.12.10-1

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
    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-2025-21643Jan 19, 2025 · netfs: Fix kernel async DIO
    22Monitor
  • ← EarlierCVE-2025-21644Jan 19, 2025 · drm/xe: Fix tlb invalidation when wedging
    22Monitor
  • Later →CVE-2025-21647Jan 19, 2025 · sched: sch_cake: add bounds checks to host bulk flow fairness counts
    28Monitor

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 Linux7673030efe0f8ca1056d3849d61784c6caa052afVendor (CNA)
Linux Linux7922b1f058fe24a93730511dd0ae2e1630920096Vendor (CNA)
Linux Linux7cb3e77e9b4e6ffa325a5559393d3283c9af3d01Vendor (CNA)
Linux Linux8fd56ad6e7c90ac2bddb0741c6b248c8c5d56ac8Vendor (CNA)
Linux Linux9340385468d056bb700b8f28df236b81fc86a079Vendor (CNA)
Linux Linuxaabe47cf5ac5e1db2ae0635f189d836f67024904Vendor (CNA)
debian:linux6.1.128-1 · 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)

—

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 (7 more)

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

All records