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Linux KernelOperating system · Linux

CVE-2025-21781

MEDIUM · 5.5 CVSS v3.1 Published 2025-02-27
Fix available
A fix is available. Upgrade to 5.4.291 / 5.10.235 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: batman-adv: fix panic during interface removal Reference counting is used to ensure that batadv_hardif_neigh_node and batadv_hard_iface are not freed before/during batadv_v_elp_throughput_metric_update work is finished. But there isn't a guarantee that the hard if will remain associated with a soft interface up until the work is finished. This fixes a crash triggered by reboot that looks like this: Call trace: batadv_v_mesh_free+0xd0/0x4dc [batman_adv] batadv_v_elp_throughput_metric_update+0x1c/0xa4 process_one_work+0x178/0x398 worker_thread+0x2e8/0x4d0 kthread+0xd8/0xdc ret_from_fork+0x10/0x20 (the batadv_v_mesh_free call is misleading, and does not actually happen) I was able to make the issue happen more reliably by changing hardif_neigh->bat_v.metric_work work to be delayed work. This allowed me to track down and confirm the fix. [[email protected]: prevent entering batadv_v_elp_get_throughput without soft_iface]

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 4.6, < 5.4.291>= 5.5, < 5.10.235>= 5.11, < 5.15.179>= 5.16, < 6.1.129>= 6.2, < 6.6.79>= 6.7, < 6.12.16>= 6.13, < 6.13.4= 6.14

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.4.291 / 5.10.235 / 5.15.179 or later
Fixed in 5.4.2915.10.2355.15.179
Vendor patch git.kernel.org →
Recommended fix High confidence

Upgrade to kernel 5.4.291+, 5.10.235+, 5.15.179+, or 6.1.129+ (or later stable release)

  1. Identify the current kernel version using `uname -r`
  2. Determine which stable kernel branch your current version belongs to based on the affected version ranges
  3. Upgrade the Linux kernel to a fixed release: 5.4.291 or later, 5.10.235 or later, 5.15.179 or later, or 6.1.129 or later
  4. On Debian/Ubuntu: `sudo apt-get update && sudo apt-get dist-upgrade` or install a specific kernel package
  5. On RHEL/CentOS: `sudo yum update kernel` or `sudo dnf update kernel`
  6. On Fedora: `sudo dnf update kernel`
  7. Reboot the system to load the new kernel: `sudo reboot`
  8. Verify the new kernel version is running with `uname -r` and confirm it is one of the fixed versions
Caveat Kernel upgrades may introduce compatibility changes with third-party modules or specific hardware drivers; ensure dependent kernel modules are compatible with the new kernel version

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-21781 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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