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CVE-2026-23450

Critical Vulnerability: CVE-2026-23450 — linux — linux_kernel

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock() Syzkaller reported a panic in smc_tcp_syn_recv_sock() [1]. smc_tcp_syn_recv_sock() is called in the TCP receive path (softirq) via icsk_af_ops->syn_recv_sock on the clcsock (TCP listening socket). It reads sk_user_data to get the smc_sock pointer. However, when the SMC listen socket is being closed concurrently, smc_close_active() sets clcsock->sk_user_data to N

Thursday, May 21, 2026linuxVulnios Threat Intelligence
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Vulnerability Snapshot

CVE-2026-23450 is rated CRITICAL — exploitation is trivial or already observed in the wild and impact is severe. Patch immediately, not on the next maintenance window.

Affected technology: linux_kernel.

Executive Summary

In the Linux kernel, the following vulnerability has been resolved:

net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock()

Syzkaller reported a panic in smc_tcp_syn_recv_sock() [1].

smc_tcp_syn_recv_sock() is called in the TCP receive path

(softirq) via icsk_af_ops->syn_recv_sock on the clcsock (TCP

listening socket). It reads sk_user_data to get the smc_sock

pointer. However, when the SMC listen socket is being closed

concurrently, smc_close_active() sets clcsock->sk_user_data

to NULL under sk_callback_lock, and then the smc_sock itself

can be freed via sock_put() in smc_release().

This leads to two issues:

1) NULL pointer dereference: sk_user_data is NULL when

accessed.

2) Use-after-free: sk_user_data is read as non-NULL, but the

smc_sock is freed before its fields (e.g., queued_smc_hs,

ori_af_ops) are accessed.

The race window looks like this (the syzkaller crash [1]

triggers via the SYN cookie path: tcp_get_cookie_sock() ->

smc_tcp_syn_recv_sock(), but the

Why It Matters

CVE-2026-23450 is rated CRITICAL severity, requiring immediate attention from security teams.

CVSS Base Score: 9.8/10

EPSS (Exploit Prediction): 0.1% probability of exploitation in the next 30 days.

Affected Technologies

Vendors: linux

Products: linux_kernel

🛡️What Defenders Should Check

  • Check if you are affected — Review your asset inventory for products listed in CVE-2026-23450.
  • Apply available patches — Visit vendor advisories for the latest security updates.
  • Monitor for exploitation — Check your SIEM/IDS logs for related indicators.

    • Use Vulnios to continuously monitor your exposure to CVE-2026-23450 and similar vulnerabilities.

    References & Sources

  • https://git.kernel.org/stable/c/1e4f873879e075bbd4eb1c644d6933303ac5eba4
  • https://git.kernel.org/stable/c/1fab5ece76fb42a761178dcd0ebcbf578377b0dd
  • https://git.kernel.org/stable/c/6d5e4538364b9ceb1ac2941a4deb86650afb3538
  • https://git.kernel.org/stable/c/cadf3da46c15523fba90d80c9955f536ee3b4023
  • https://git.kernel.org/stable/c/f00fc26c8a06442b225a350fe000c0a11483e6a3
  • https://git.kernel.org/stable/c/f315277856caeafcd996c2611afc085ca2d53275
  • https://git.kernel.org/stable/c/fd7579f0a2c84ba8a7d4f206201b50dc8ddf90c2

    • How Vulnios Detects This

    Vulnios scans for this vulnerability using Trivy and Grype for CVE matching against your container images and OS package manifests. Run a scan against your environment to see whether you are exposed; findings are linked back to the original CVE record so triage starts with the patch path already known.

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    Affected Products

    linux_kernel

    Sources

    Related Threat Alerts

    Frequently Asked Questions

    What is CVE-2026-23450?

    CVE-2026-23450 is a critical-severity vulnerability tracked under the Common Vulnerabilities and Exposures program. In the Linux kernel, the following vulnerability has been resolved:

    net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock()

    Syzkaller reported a panic in smc_tcp_syn_recv_sock() [1].

    smc_t

    Am I affected?

    Check whether your environment runs linux_kernel. If you operate any of those, treat yourself as in scope until you have evidence otherwise. A Vulnios scan will identify the exact assets carrying the affected version.

    How urgent is the response?

    Critical: do not wait for your normal patch cycle. Verify exposure today, apply the vendor patch immediately, and add detection rules for any post-exploit indicators.

    How do I remediate?

    Apply the vendor patch listed in the upstream advisory linked under Sources. If the patch is not yet available, follow the vendor-supplied workaround (often a config flag or feature disable) and add detections for the published exploit pattern in your SIEM. Re-scan after the patch lands to confirm the finding clears.

    Where can I track exploitation activity?

    Watch CISA's Known Exploited Vulnerabilities catalog for CVE-2026-23450. Cross-reference with public exploit databases and your own SIEM/IDS for indicator-of-compromise patterns. Vulnios tracks KEV status automatically and surfaces it on the asset findings view.

    How does Vulnios help with this?

    Vulnios continuously cross-references your asset inventory against the live CVE feed (NVD, vendor advisories, CISA KEV, and curated OSINT). When a new CVE matches your environment, you get a prioritized finding with the severity, KEV status, exploit-prediction (EPSS), and a direct path to the vendor patch. You can start a free scan from the homepage.

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