CVE-2025-40240 sctp: avoid NULL dereference when chunk data buffer is missing
High 7.5
Published
Updated
Check this codebase for CVE-2025-40240 and fix it if it is affected.
What it is: CVE-2025-40240 is a high-severity vulnerability in Linux, published on 4 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-40240 in the wild and no public exploit code.
Affected product: Linux. 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-2025-40240/ (Markdown: https://insights.sbomify.com/CVE-2025-40240/index.md)
A NULL pointer dereference in the Linux kernel SCTP implementation allows attackers to cause a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-40240?
CVE-2025-40240 is a high-severity vulnerability in Linux, published on 4 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
sctp: avoid NULL dereference when chunk data buffer is missing
chunk->skb pointer is dereferenced in the if-block where it's supposed to be NULL only.
chunk->skb can only be NULL if chunk->head_skb is not. Check for frag_list instead and do it just before replacing chunk->skb. We're sure that otherwise chunk->skb is non-NULL because of outer if() condition.
Which versions are affected by CVE-2025-40240?
Linux distribution packages (40)
bpftool-debuginfo Red Hat:rhel_eus:9.4::appstream | All versions | 0:7.3.0-427.115.1.el9_4 |
kernel-64k-debug-debuginfo Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-64k-debug-devel Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-64k-debug-devel-matched Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-64k-debuginfo Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-64k-devel Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-64k-devel-matched Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-debug-debuginfo Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-debug-devel Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-debug-devel-matched Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-debuginfo Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-debuginfo-common-aarch64 Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-debuginfo-common-ppc64le Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-debuginfo-common-s390x Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-debuginfo-common-x86_64 Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-devel Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-devel-matched Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-doc Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-rt-debug-debuginfo Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-rt-debuginfo Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-tools-debuginfo Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-zfcpdump-debuginfo Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-zfcpdump-devel Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-zfcpdump-devel-matched Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
libperf-debuginfo Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
perf Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
perf-debuginfo Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
python3-perf-debuginfo Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
rtla Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
rv Red Hat:rhel_eus:9.4::appstream | All versions | 0:5.14.0-427.115.1.el9_4 |
bpftool Red Hat:rhel_eus:9.4::baseos | All versions | 0:7.3.0-427.115.1.el9_4 |
bpftool-debuginfo Red Hat:rhel_eus:9.4::baseos | All versions | 0:7.3.0-427.115.1.el9_4 |
kernel Red Hat:rhel_eus:9.4::baseos | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-64k Red Hat:rhel_eus:9.4::baseos | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-64k-core Red Hat:rhel_eus:9.4::baseos | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-64k-debug Red Hat:rhel_eus:9.4::baseos | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-64k-debug-core Red Hat:rhel_eus:9.4::baseos | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-64k-debug-debuginfo Red Hat:rhel_eus:9.4::baseos | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-64k-debug-modules Red Hat:rhel_eus:9.4::baseos | All versions | 0:5.14.0-427.115.1.el9_4 |
kernel-64k-debug-modules-core Red Hat:rhel_eus:9.4::baseos | All versions | 0:5.14.0-427.115.1.el9_4 |
How do I fix CVE-2025-40240?
Apply the vendor's patch.
Is CVE-2025-40240 being exploited?
There is no known exploitation of CVE-2025-40240 in the wild and no public exploit code.
Sources
Also known as AZL-71375, BELL-CVE-2025-40240, DEBIAN-CVE-2025-40240, GHSA-p7wh-phc3-g7xr, RHSA-2026:4899, ROOT-OS-DEBIAN-11-CVE-2025-40240 and 2 more.