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NVD / CVE Program· CNA Linux

CVE-2025-21823: batman-adv: Drop unmanaged ELP metric worker

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: 0.24% (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 0fdc3c166ac17b26014313fa2b93696354511b24, 1c334629176c2d644befc31a20d4bf75542f7631, 3c0e0aecb78cb2a2ca1dc701982d08fedb088dc6.
  • Severity is disputed: the assigning authority (CNA) scores it 7.8, NVD 5.5.

Low priority for now. Upgrade to Linux Linux 0fdc3c166ac17b26014313fa2b93696354511b24, 1c334629176c2d644befc31a20d4bf75542f7631, 3c0e0aecb78cb2a2ca1dc701982d08fedb088dc6 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: batman-adv: Drop unmanaged ELP metric worker The ELP worker needs to calculate new metric values for all neighbors "reachable" over an interface. Some of the used metric sources require locks which might need to sleep. This sleep is incompatible with the RCU list iterator used for the recorded neighbors. The initial approach to work around of this problem was to queue another work item per neighbor and then run this in a new context. Even when this solved the RCU vs might_sleep() conflict, it has a major problems: Nothing was stopping the work item in case it is not needed anymore - for example because one of the related interfaces was removed or the batman-adv module was unloaded - resulting in potential invalid memory accesses. Directly canceling the metric worker also has various problems: * cancel_work_sync for a to-be-deactivated interface is called with rtnl_lock held. But the code in the ELP metric worker also tries to use rtnl_lock() - which will never return in this case. This also means that cancel_work_sync would never return because it is waiting for the worker to finish. * iterating over the neighbor list for the to-be-deactivated interface is currently done using the RCU specific methods. Which means that it is possible to miss items when iterating over it without the associated spinlock - a behaviour which is acceptable for a periodic metric check but not for a cleanup routine (which must "stop" all still running workers) The better approch is to get rid of the per interface neighbor metric worker and handle everything in the interface worker. The original problems are solved by: * creating a list of neighbors which require new metric information inside the RCU protected context, gathering the metric according to the new list outside the RCU protected context * only use rcu_trylock inside metric gathering code to avoid a deadlock when the cancel_delayed_work_sync is called in the interface removal code (which is called with the rtnl_lock held)

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Feb 27, 2025
Updated
Aug 5, 2026
EPSS
0.2% · 15th 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 · 0.2%

CNA vs NVD score

NVD
5.5
CNA · Linux
7.8
2.3 point gap

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

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

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  • 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?

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 kernel4.6 and later · before 5.4.291
  • linux linux kernel5.5 and later · before 5.10.235
  • linux linux kernel5.11 and later · before 5.15.179
  • linux linux kernel5.16 and later · before 6.1.129
  • linux linux kernel6.2 and later · before 6.6.79
  • linux linux kernel6.7 and later · before 6.12.16
  • linux linux kernel6.13 and later · before 6.13.4
  • 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

    • 4.6affected
    • c833484e5f3872a38fe232c663586069d5ad9645 and later · before 1c334629176c2d644befc31a20d4bf75542f7631affected · git
    • c833484e5f3872a38fe232c663586069d5ad9645 and later · before a0019971f340ae02ba54cf1861f72da7e03e6b66affected · git
    • c833484e5f3872a38fe232c663586069d5ad9645 and later · before 3c0e0aecb78cb2a2ca1dc701982d08fedb088dc6affected · git
    • c833484e5f3872a38fe232c663586069d5ad9645 and later · before 781a06fd265a8151f7601122d9c2e985663828ffaffected · git
    • c833484e5f3872a38fe232c663586069d5ad9645 and later · before a7aa2317285806640c844acd4cd2cd768e395264affected · git
    • c833484e5f3872a38fe232c663586069d5ad9645 and later · before 0fdc3c166ac17b26014313fa2b93696354511b24affected · git
    • c833484e5f3872a38fe232c663586069d5ad9645 and later · before af264c2a9adc37f4bdf88ca7f3affa15d8c7de9eaffected · git
    • c833484e5f3872a38fe232c663586069d5ad9645 and later · before 8c8ecc98f5c65947b0070a24bac11e12e47cc65daffected · git
    • before 4.6not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.129-16.1.129-1
Debian:13linuxbefore 6.12.16-16.12.16-1

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-2025-21821Feb 27, 2025 · fbdev: omap: use threaded IRQ for LCD DMA
    22Monitor
  • ← EarlierCVE-2025-21822Feb 27, 2025 · ptp: vmclock: Set driver data before its usage
    22Monitor
  • Later →CVE-2025-21824Feb 27, 2025 · gpu: host1x: Fix a use of uninitialized mutex
    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 Linux0fdc3c166ac17b26014313fa2b93696354511b24Vendor (CNA)
Linux Linux1c334629176c2d644befc31a20d4bf75542f7631Vendor (CNA)
Linux Linux3c0e0aecb78cb2a2ca1dc701982d08fedb088dc6Vendor (CNA)
Linux Linux781a06fd265a8151f7601122d9c2e985663828ffVendor (CNA)
Linux Linux8c8ecc98f5c65947b0070a24bac11e12e47cc65dVendor (CNA)
Linux Linuxa0019971f340ae02ba54cf1861f72da7e03e6b66Vendor (CNA)
Linux Linuxa7aa2317285806640c844acd4cd2cd768e395264Vendor (CNA)
Linux Linuxaf264c2a9adc37f4bdf88ca7f3affa15d8c7de9eVendor (CNA)
debian:linux6.1.129-1 · 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 (9 more)

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

All records