What’s Vulnerable › Vulnerabilities

CVE-2025-40240: sctp: avoid NULL dereference when chunk data buffer is missing

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-12-04 · updated 2026-10-19

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.

Affected products

• Linux kernel: 4.8 — fixed in 6.18

How to fix

Upgrade to a fixed version: Linux kernel 6.18. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/03e80a4b04ef1fb2c61dd63216ab8d3a5dcb196f
• https://git.kernel.org/stable/c/08165c296597075763130919f2aae59b5822f016
• https://git.kernel.org/stable/c/441f0647f7673e0e64d4910ef61a5fb8f16bfb82
• https://git.kernel.org/stable/c/4f6da435fb5d8a21cbf8cae5ca5a2ba0e1012b71
• https://git.kernel.org/stable/c/61cda2777b07d27459f5cac5a047c3edf9c8a1a9
• https://git.kernel.org/stable/c/7a832b0f99be19df608cb75c023f8027b1789bd1
• https://git.kernel.org/stable/c/89b465b54227c245ddc7cc9ed822231af21123ef
• https://git.kernel.org/stable/c/cb9055ba30306ede4ad920002233d0659982f1cb

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