CVE-2026-23450: Linux kernel · net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock()
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in 5.15.0-1111.118~20.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 38% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1111.118~20.04.1, 5.15.0-1116.125~20.04.1, 5.15.0-1111.121~20.04.1 +69
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 3 Apr 2026
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@6.17.0-40.40?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1019.19?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1020.20?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@6.17.0-1020.22?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1018.18?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.
AI-suggested
A patch is available and has been released by Ubuntu in multiple kernel packages including linux-image-6.17 and linux-image-oem-6.17 series. Users should update their Linux kernel to the fixed versions listed in Ubuntu security notices USN-8490-1 and USN-8491-1 and reboot their systems to apply the fixes. Due to an ABI change in the kernel update, all third-party kernel modules must be recompiled and reinstalled after updating. No other mitigation is required as the vulnerability is addressed by the official fixes.
Description
A high-severity vulnerability (CVE-2026-23450) in the Linux kernel's SMC TCP socket handling was resolved. The flaw involved a NULL pointer dereference and use-after-free (UAF) condition in the smc_tcp_syn_recv_sock() function, triggered by a race condition when closing SMC listen sockets concurrently. This vulnerability could lead to system crashes or potentially allow an attacker to compromise the system. Multiple Linux kernel subsystems were updated to address this and other issues. Ubuntu has released patched kernel versions to fix this vulnerability, requiring system updates and reboots. Due to an ABI change, recompilation of third-party kernel modules is necessary after updating. The vulnerability affects specific Linux kernel versions prior to the patched releases.
References
- ubuntu.com/security/CVE-2026-23450 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23450 (opens in a new tab)
- git.kernel.org/linus/6d5e4538364b9ceb1ac2941a4deb86650afb3538 (opens in a new tab)
- git.kernel.org/stable/c/1e4f873879e075bbd4eb1c644d6933303ac5eba4 (opens in a new tab)
- git.kernel.org/stable/c/1fab5ece76fb42a761178dcd0ebcbf578377b0dd (opens in a new tab)
- git.kernel.org/stable/c/6d5e4538364b9ceb1ac2941a4deb86650afb3538 (opens in a new tab)
- git.kernel.org/stable/c/cadf3da46c15523fba90d80c9955f536ee3b4023 (opens in a new tab)
- git.kernel.org/stable/c/f00fc26c8a06442b225a350fe000c0a11483e6a3 (opens in a new tab)
- git.kernel.org/stable/c/fd7579f0a2c84ba8a7d4f206201b50dc8ddf90c2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8490-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8491-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8493-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8497-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8498-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8499-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8493-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8508-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8492-3 (opens in a new tab)