NVD / CVE Program· CNA Linux

CVE-2025-21762: arp: use RCU protection in arp_xmit()

Noroxi assessment

Priority: Monitor (action score 32/100)

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: 0.66% (FIRST EPSS); higher than 51.8% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
Fixed version: Linux Linux 01d1b5c9abcaff29a43f1d17a19c33eec92c7dbe, 10f555e3f573d004ae9d89b3276abb58c4ede5c3, 2c331718d3389b6c5f6855078ab7171849e016bd; 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 01d1b5c9abcaff29a43f1d17a19c33eec92c7dbe, 10f555e3f573d004ae9d89b3276abb58c4ede5c3, 2c331718d3389b6c5f6855078ab7171849e016bd; 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: arp: use RCU protection in arp_xmit() arp_xmit() can be called without RTNL or RCU protection. Use RCU protection to avoid potential UAF.

HighCVSS 8.1 · v3.1—No exploit Fix available

BDU:2025-04523

Published: Feb 27, 2025
Updated: Oct 15, 2026
EPSS: 0.6% · 51th percentile
CWE: CWE-416

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 32 / 40 · 8.1 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.6%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · Linux: 8.1; NVD has not scored this yet; the score shown is the CNA’s.

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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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.

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 kernel4.4 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
- 4.4affected
- 29a26a56803855a79dbd028cd61abee56237d6e5 and later · before 10f555e3f573d004ae9d89b3276abb58c4ede5c3affected · git
- 29a26a56803855a79dbd028cd61abee56237d6e5 and later · before 307cd1e2d3cb1cbc6c40c679cada6d7168b18431affected · git
- 29a26a56803855a79dbd028cd61abee56237d6e5 and later · before d9366ac2f956a1948b68c0500f84a3462ff2ed8aaffected · git
- 29a26a56803855a79dbd028cd61abee56237d6e5 and later · before f189654459423d4d48bef2d120b4bfba559e6039affected · git
- 29a26a56803855a79dbd028cd61abee56237d6e5 and later · before e9f4dee534eb1b225b0a120395ad9bc2afe164d3affected · git
- 29a26a56803855a79dbd028cd61abee56237d6e5 and later · before 01d1b5c9abcaff29a43f1d17a19c33eec92c7dbeaffected · git
- 29a26a56803855a79dbd028cd61abee56237d6e5 and later · before 2c331718d3389b6c5f6855078ab7171849e016bdaffected · git
- 29a26a56803855a79dbd028cd61abee56237d6e5 and later · before a42b69f692165ec39db42d595f4f65a4c8f42e44affected · git
- before 4.4not 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 6.1.129-1	6.1.129-1
Debian:13	linux	before 6.12.16-1	6.12.16-1

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-2025-21760Feb 27, 2025 · ndisc: extend RCU protection in ndisc_send_skb()
43Plan
← EarlierCVE-2025-21761Feb 27, 2025 · openvswitch: use RCU protection in ovs_vport_cmd_fill_info()
31Monitor
Later →CVE-2025-21763Feb 27, 2025 · neighbour: use RCU protection in __neigh_notify()
31Monitor

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	01d1b5c9abcaff29a43f1d17a19c33eec92c7dbe	Vendor (CNA)
Linux Linux	10f555e3f573d004ae9d89b3276abb58c4ede5c3	Vendor (CNA)
Linux Linux	2c331718d3389b6c5f6855078ab7171849e016bd	Vendor (CNA)
Linux Linux	307cd1e2d3cb1cbc6c40c679cada6d7168b18431	Vendor (CNA)
Linux Linux	a42b69f692165ec39db42d595f4f65a4c8f42e44	Vendor (CNA)
Linux Linux	d9366ac2f956a1948b68c0500f84a3462ff2ed8a	Vendor (CNA)
Linux Linux	e9f4dee534eb1b225b0a120395ad9bc2afe164d3	Vendor (CNA)
Linux Linux	f189654459423d4d48bef2d120b4bfba559e6039	Vendor (CNA)
azl3 kernel 6.6.78.1-3 on Azure Linux 3.0	6.6.82.1-1 · CBL-Mariner Releases	Microsoft (MSRC)
azl3 kernel 6.6.82.1-1 on Azure Linux 3.0	6.6.82.1-1 · CBL-Mariner Releases	Microsoft (MSRC)
cbl2 kernel 5.15.176.3-3 on CBL Mariner 2.0	5.15.180.1-1 · CBL-Mariner Releases	Microsoft (MSRC)
cbl2 kernel 5.15.176.3-3 on CBL-Mariner 2.0	5.15.180.1-1 · CBL-Mariner Releases	Microsoft (MSRC)
cbl2 kernel 5.15.180.1-1 on CBL Mariner 2.0	5.15.180.1-1 · CBL-Mariner Releases	Microsoft (MSRC)
debian:linux	6.1.129-1 · 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

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
Special conditions such as timing or configuration are required.

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: Network
Attack complexity: High
Privileges required: None
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:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

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, 10:09 PM UTC

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

References

git.kernel.org/stable/c/01d1b5c9abcaff29a43f1d17a19c33eec92c7dbe

Show all references (12 more)

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

All records