Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock() Syzkaller… (CVE-2026-23450)
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.
AI Analysis
Technical Summary
CVE-2026-23450 is a vulnerability in the Linux kernel's SMC (Shared Memory Communications) TCP socket implementation. The issue arises in the smc_tcp_syn_recv_sock() function, which is called during the TCP receive path. A race condition occurs when the SMC listen socket is closed concurrently: smc_close_active() sets the sk_user_data pointer to NULL under a lock, and the associated smc_sock structure can be freed shortly thereafter. This leads to two critical issues: a NULL pointer dereference when sk_user_data is accessed as NULL, and a use-after-free when smc_sock is accessed after being freed. The vulnerability was discovered via Syzkaller fuzzing and could cause kernel panics or potentially allow attackers to compromise system integrity. Ubuntu's security advisories USN-8490-1 and USN-8491-1 confirm the availability of patches in Linux kernel versions 6.17.x and related OEM and cloud kernels. Users must update to these fixed versions and reboot systems. The update involves an ABI change requiring recompilation of third-party kernel modules.
Potential Impact
This vulnerability can cause a kernel panic due to NULL pointer dereference or use-after-free conditions in the TCP receive path, potentially leading to denial of service or system compromise. The CVSS 3.1 score is 9.8 (critical impact on confidentiality, integrity, and availability). An attacker could exploit this flaw remotely without privileges or user interaction. The vulnerability affects the Linux kernel's network stack, specifically the SMC TCP socket handling, which could be leveraged to compromise affected systems.
Mitigation Recommendations
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.
Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock() Syzkaller… (CVE-2026-23450)
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.
CVSS v3.1
Score 9.8critical
Affected software
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protected]~18.04.1?arch=source&distro=bionicpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.2?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]+cvm1.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/[email protected]~20.04.3?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/[email protected]?arch=source&distro=focalpkg:deb/ubuntu/[email protected]?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/[email protected]?arch=source&distro=focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/[email protected]~20.04.1?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/[email protected]?arch=source&distro=focalpkg:deb/ubuntu/[email 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protected]~22.04.1?arch=source&distro=jammypkg:deb/ubuntu/[email protected]~22.04.1?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]~22.04.1?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]~22.04.1?arch=source&distro=jammypkg:deb/ubuntu/[email protected]~22.04.1?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]~22.04.1?arch=source&distro=jammypkg:deb/ubuntu/[email protected]~22.04.1?arch=source&distro=jammypkg:deb/ubuntu/[email protected]~22.04.1?arch=source&distro=jammypkg:deb/ubuntu/[email protected]~22.04.1?arch=source&distro=jammypkg:deb/ubuntu/[email protected]~22.04.1?arch=source&distro=jammypkg:deb/ubuntu/[email protected]~22.04.1?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=bluefield/jammypkg:deb/ubuntu/[email protected]+fips1?arch=source&distro=fips-updates/jammypkg:deb/ubuntu/[email protected]+fips1?arch=source&distro=fips-updates/jammypkg:deb/ubuntu/[email protected]+fips1?arch=source&distro=fips-updates/jammypkg:deb/ubuntu/[email protected]+fips1?arch=source&distro=fips-updates/jammypkg:deb/ubuntu/[email protected]?arch=source&distro=realtime/jammypkg:deb/ubuntu/[email protected]?arch=source&distro=realtime/jammypkg:deb/ubuntu/[email protected]~22.04.1?arch=source&distro=realtime/jammypkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=bluefield/noblepkg:deb/ubuntu/[email protected]+fips1?arch=source&distro=fips-updates/noblepkg:deb/ubuntu/[email protected]+fips1?arch=source&distro=fips-updates/noblepkg:deb/ubuntu/[email protected]+fips1?arch=source&distro=fips-updates/noblepkg:deb/ubuntu/[email protected]+fips1?arch=source&distro=fips-updates/noblepkg:deb/ubuntu/[email protected]?arch=source&distro=realtime/noblepkg:deb/ubuntu/[email protected]?arch=source&distro=realtime/noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=realtime/noblepkg:deb/ubuntu/[email protected]~24.04.1?arch=source&distro=realtime/noblepkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=questingRun on your own infrastructure? 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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-23450 is a vulnerability in the Linux kernel's SMC (Shared Memory Communications) TCP socket implementation. The issue arises in the smc_tcp_syn_recv_sock() function, which is called during the TCP receive path. A race condition occurs when the SMC listen socket is closed concurrently: smc_close_active() sets the sk_user_data pointer to NULL under a lock, and the associated smc_sock structure can be freed shortly thereafter. This leads to two critical issues: a NULL pointer dereference when sk_user_data is accessed as NULL, and a use-after-free when smc_sock is accessed after being freed. The vulnerability was discovered via Syzkaller fuzzing and could cause kernel panics or potentially allow attackers to compromise system integrity. Ubuntu's security advisories USN-8490-1 and USN-8491-1 confirm the availability of patches in Linux kernel versions 6.17.x and related OEM and cloud kernels. Users must update to these fixed versions and reboot systems. The update involves an ABI change requiring recompilation of third-party kernel modules.
Potential Impact
This vulnerability can cause a kernel panic due to NULL pointer dereference or use-after-free conditions in the TCP receive path, potentially leading to denial of service or system compromise. The CVSS 3.1 score is 9.8 (critical impact on confidentiality, integrity, and availability). An attacker could exploit this flaw remotely without privileges or user interaction. The vulnerability affects the Linux kernel's network stack, specifically the SMC TCP socket handling, which could be leveraged to compromise affected systems.
Mitigation Recommendations
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.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-23450
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:16.04:LTS","Ubuntu:18.04:LTS","Ubuntu:20.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:22.04:LTS","Ubuntu:Nvidia-BlueField:22.04:LTS","Ubuntu:Pro:FIPS-updates:22.04:LTS","Ubuntu:Pro:Realtime:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:Nvidia-BlueField:24.04:LTS","Ubuntu:Pro:FIPS-updates:24.04:LTS","Ubuntu:Pro:Realtime:24.04:LTS","Ubuntu:25.10"]
- Cvss Version
- 4.0
Threat ID: 6a58b4dc68715ace43dae4f6
Added to database: 07/16/2026, 10:39:24 UTC
Last enriched: 08/01/2026, 06:07:33 UTC
Last updated: 09/10/2026, 19:36:52 UTC
Views: 19
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