CVE-2025-21760: In the Linux kernel, the following vulnerability has been resolved: ndisc: extend RCU protection in ndisc_sen

Q: How do I fix CVE-2025-21760?

linux kernel: upgrade to 5.4.291, 5.10.235, 5.15.179, 6.1.129, 6.6.79, 6.12.16, 6.13.4. Exact commands for each OS are on this page.

Q: Is CVE-2025-21760 being exploited?

CVE-2025-21760 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2025-21760 affect?

CVE-2025-21760 affects linux kernel. Severity is high (CVSS 8.1). In the Linux kernel, the following vulnerability has been resolved: ndisc: extend RCU protection in ndisc_send_skb() ndisc_send_skb() can be called without RTNL or RCU held. Acquire rcu_read_lock() earlier, so that we can use dev_net_rcu

Q: How urgent is CVE-2025-21760?

Priority 63/100. High severity; EPSS top 1%: very likely to be exploited; Remotely exploitable, no login, no user action; On your watchlist

This week

HIGH 8.1REMOTEWATCHLISTUPGRADE

CVE-2025-21760 is a high-severity flaw (CVSS 8.1) affecting linux kernel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In the Linux kernel, the following vulnerability has been resolved: ndisc: extend RCU protection in ndisc_send_skb() ndisc_send_skb() can be called without RTNL or RCU held. Acquire rcu_read_lock() earlier, so that we can use dev_net_rcu() and avoid a potential UAF.

Why this priority

High severity
EPSS top 1%: very likely to be exploited
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	38.0% (top 1%)
CISA exploited list	No
Weakness	CWE-416
Published	2025-02-27
Last modified	2026-10-15

Publisher (CNA): kernel.org · Vendor: linux

Last updated 2026-10-15 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-02-27 03:15 UTCPublished CVE record published
2026-10-15 02:17 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 2.6.26 and < 5.4.291 · >= 5.5 and < 5.10.235 · >= 5.11 and < 5.15.179 · >= 5.16 and < 6.1.129 · >= 6.2 and < 6.6.79 · >= 6.7 and < 6.12.16 · >= 6.13 and < 6.13.4 · 6.14 rc1

Fixed in: 5.4.291, 5.10.235, 5.15.179, 6.1.129, 6.6.79, 6.12.16, 6.13.4

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

Fedora 46 · opensips · FIXED · 4.0.3-1.fc46 · FEDORA-2026-6700a0026c · source

sudo dnf upgrade --advisory=FEDORA-2026-6700a0026c

Fedora ELN · ibus-typing-booster · FIXED · 2.31.3-1.eln159 · FEDORA-2026-c895c68d60 · source

sudo dnf upgrade --advisory=FEDORA-2026-c895c68d60

Ubuntu 24.10 · linux · FIXED · 6.11.0-26.26

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.11.0-26.26" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 20.04 · linux · FIXED · 5.4.0-216.236

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "5.4.0-216.236" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · linux · FIXED · 5.15.0-140.150

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "5.15.0-140.150" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 25.04 · linux · NOT AFFECTED

Ubuntu 24.04 · linux · FIXED · 6.8.0-78.78

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.8.0-78.78" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · linux · FIXED · 6.1.129-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.1.129-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · linux · FIXED · 6.12.16-1

sudo apt update && sudo apt install --only-upgrade linux dpkg --compare-versions "$(dpkg-query -W -f='${Version}' linux)" ge "6.12.16-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · kernel · DEFERRED

RHEL 6 · kernel · DEFERRED

RHEL 7 · kernel · DEFERRED

RHEL 7 · kernel-rt · DEFERRED

RHEL 8 · kernel · NO FIX YET

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2025-915 · source

sudo dnf update --advisory=ALAS2023-2025-915

Amazon Linux 2 · see advisory · FIXED · ALAS2-2025-2826 · source

sudo yum update --advisory=ALAS2-2025-2826

Amazon Linux 1 · see advisory · FIXED · ALAS-2025-1970 · source

sudo yum update --advisory=ALAS-2025-1970

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: cert-portal.siemens.com/productcert/html/ssa-019113.html
Write-up: cert-portal.siemens.com/productcert/html/ssa-265688.html
Write-up: cert-portal.siemens.com/productcert/html/ssa-457936.html

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-21760?

linux kernel: upgrade to 5.4.291, 5.10.235, 5.15.179, 6.1.129, 6.6.79, 6.12.16, 6.13.4. Exact commands for each OS are on this page.

Is CVE-2025-21760 being exploited?

CVE-2025-21760 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-21760 affect?

CVE-2025-21760 affects linux kernel. Severity is high (CVSS 8.1). In the Linux kernel, the following vulnerability has been resolved: ndisc: extend RCU protection in ndisc_send_skb() ndisc_send_skb() can be called without RTNL or RCU held. Acquire rcu_read_lock() earlier, so that we can use dev_net_rcu

How urgent is CVE-2025-21760?

Priority 63/100. High severity; EPSS top 1%: very likely to be exploited; Remotely exploitable, no login, no user action; On your watchlist

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References

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