CVE-2025-40240: Linux kernel · sctp: avoid NULL dereference when chunk data buffer is missing
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.5 High · fixed in 5.15.0-1100.107~20.04.2 : patch Linux kernel soon.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1100.107~20.04.2, 5.15.0-1110.119~20.04.1, 5.15.0-1100.109~20.04.1 +67
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 4 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux@6.17.0-14.14?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1007.7?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1008.8?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1007.7?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1007.7?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
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.
References
- ubuntu.com/security/CVE-2025-40240 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-40240 (opens in a new tab)
- git.kernel.org/linus/441f0647f7673e0e64d4910ef61a5fb8f16bfb82 (opens in a new tab)
- git.kernel.org/stable/c/03e80a4b04ef1fb2c61dd63216ab8d3a5dcb196f (opens in a new tab)
- git.kernel.org/stable/c/08165c296597075763130919f2aae59b5822f016 (opens in a new tab)
- git.kernel.org/stable/c/441f0647f7673e0e64d4910ef61a5fb8f16bfb82 (opens in a new tab)
- git.kernel.org/stable/c/4f6da435fb5d8a21cbf8cae5ca5a2ba0e1012b71 (opens in a new tab)
- git.kernel.org/stable/c/61cda2777b07d27459f5cac5a047c3edf9c8a1a9 (opens in a new tab)
- git.kernel.org/stable/c/7a832b0f99be19df608cb75c023f8027b1789bd1 (opens in a new tab)
- git.kernel.org/stable/c/89b465b54227c245ddc7cc9ed822231af21123ef (opens in a new tab)
- git.kernel.org/stable/c/cb9055ba30306ede4ad920002233d0659982f1cb (opens in a new tab)
- ubuntu.com/security/notices/USN-8029-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8030-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8034-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8029-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-5 (opens in a new tab)