CVE-2025-21764 ndisc: use RCU protection in ndisc_alloc_skb()
High 7.8
Published
Updated
Check this codebase for CVE-2025-21764 and fix it if it is affected.
What it is: CVE-2025-21764 is a high-severity use after free vulnerability in Linux kernel, published on 27 Feb 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-21764 in the wild and no public exploit code.
Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.
Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.
Reference: https://insights.sbomify.com/CVE-2025-21764/ (Markdown: https://insights.sbomify.com/CVE-2025-21764/index.md)
A use-after-free vulnerability in the Linux kernel's ndisc module allows attackers to potentially execute code or cause a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-21764?
CVE-2025-21764 is a high-severity use after free vulnerability in Linux kernel, published on 27 Feb 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ndisc: use RCU protection in ndisc_alloc_skb()
ndisc_alloc_skb() can be called without RTNL or RCU being held.
Add RCU protection to avoid possible UAF.
Weakness: CWE-416
Which versions are affected by CVE-2025-21764?
It affects 1 product.
Linux distribution packages (40)
bpftool Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
bpftool-debuginfo Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-abi-whitelists Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-core Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-debug Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-debug-core Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-debug-debuginfo Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-debug-devel Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-debug-modules Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-debug-modules-extra Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-debuginfo Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-debuginfo-common-x86_64 Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-devel Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-doc Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-modules Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-modules-extra Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-tools Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-tools-debuginfo Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
kernel-tools-libs Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
perf Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
perf-debuginfo Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
python3-perf Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
python3-perf-debuginfo Red Hat:rhel_aus:8.2::baseos | All versions | 0:4.18.0-193.154.1.el8_2 |
bpftool-debuginfo Red Hat:rhel_e4s:9.2::appstream | All versions | 0:7.0.0-284.121.1.el9_2 |
kernel-64k-debug-debuginfo Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
kernel-64k-debug-devel Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
kernel-64k-debug-devel-matched Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
kernel-64k-debuginfo Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
kernel-64k-devel Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
kernel-64k-devel-matched Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
kernel-debug-debuginfo Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
kernel-debug-devel Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
kernel-debug-devel-matched Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
kernel-debuginfo Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
kernel-debuginfo-common-aarch64 Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
kernel-debuginfo-common-ppc64le Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
kernel-debuginfo-common-s390x Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
kernel-debuginfo-common-x86_64 Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
kernel-devel Red Hat:rhel_e4s:9.2::appstream | All versions | 0:5.14.0-284.121.1.el9_2 |
Products include Linux kernel.
How do I fix CVE-2025-21764?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2025-21764 being exploited?
There is no known exploitation of CVE-2025-21764 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-58898, AZL-58925, BELL-CVE-2025-21764, DEBIAN-CVE-2025-21764, GHSA-j8mq-pfgm-36r2, RHSA-2025:9490 and 4 more.