CVE-2026-23450: Linux kernel · net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock()
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 9.8 Critical · fixed in fd7579f0a2c84ba8a7d4f206201b50dc8ddf90c2 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 14:18 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.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers can reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in fd7579f0a2c84ba8a7d4f206201b50dc8ddf90c2, f315277856caeafcd996c2611afc085ca2d53275, f00fc26c8a06442b225a350fe000c0a11483e6a3 +5
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 |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in– |
AI-suggested
A fix is available and has been applied in Linux kernel versions 5.15.203 and later, as well as in version 5.18. Users and administrators should upgrade affected Linux kernel versions to these fixed releases or later to mitigate this vulnerability. No additional mitigation steps are required beyond applying the official patch.
Description
CVE-2026-23450 is a critical vulnerability in the Linux kernel's SMC (Shared Memory Communications) TCP handshake path. It involves a race condition leading to a NULL pointer dereference and use-after-free (UAF) in the smc_tcp_syn_recv_sock() function. This occurs when the SMC listen socket is closed concurrently while the TCP receive path accesses freed memory. The flaw can cause kernel crashes and potentially allow denial of service or other impacts. The issue is fixed by introducing RCU-based synchronization and refcount checks to safely access the smc_sock structure during the TCP handshake.
References
- git.kernel.org/stable/c/f315277856caeafcd996c2611afc085ca2d53275 (opens in a new tab)
- git.kernel.org/stable/c/1e4f873879e075bbd4eb1c644d6933303ac5eba4 (opens in a new tab)
- git.kernel.org/stable/c/f00fc26c8a06442b225a350fe000c0a11483e6a3 (opens in a new tab)
- git.kernel.org/stable/c/cadf3da46c15523fba90d80c9955f536ee3b4023 (opens in a new tab)
- git.kernel.org/stable/c/fd7579f0a2c84ba8a7d4f206201b50dc8ddf90c2 (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)
- cert-portal.siemens.com/productcert/html/ssa-082556.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)