In the Linux kernel, the following vulnerability has been resolved: bpf: use kvfree() for replaced sysctl write buffer proc_sys_call_handler()… (CVE-2026-63809)
A memory management vulnerability in the Linux kernel's BPF subsystem was resolved by correcting the deallocation method of a sysctl write buffer in proc_sys_call_handler(). The issue involved improper freeing of memory allocated with kvzalloc(), which may use vmalloc() internally, by using kfree(), potentially causing memory corruption. The fix replaces kfree() with kvfree() to safely handle all allocation types. The vulnerability was confirmed in kernel versions around 7.1-rc4 and 7.1-rc5. No known exploits are reported in the wild.
AI Analysis
Technical Summary
The Linux kernel vulnerability CVE-2026-63809 involves incorrect memory deallocation in proc_sys_call_handler(), where a buffer allocated with kvzalloc() (which can fall back to vmalloc()) was freed using kfree(), leading to potential memory corruption. The correct function kvfree() was introduced to handle both kmalloc and kvzalloc/vmalloc allocations safely. The bug was identified through experimental memory management analysis and reproduced on kernel version 7.1-rc4 with KASAN and CONFIG_FAILSLAB enabled. Applying the fix prevents kernel oops and memory faults triggered by this improper free operation.
Potential Impact
Improper memory deallocation can cause kernel memory corruption, leading to kernel crashes (oops) and instability. While no exploits are known in the wild, this vulnerability could potentially be leveraged to cause denial of service or other unpredictable kernel behavior due to memory corruption.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to replace kfree() with kvfree() for the affected sysctl write buffer deallocation. Users and administrators should apply the official kernel updates that include this fix. Patch status is not explicitly stated in the provided data; therefore, check the vendor's Linux kernel advisory or mainline kernel repositories for the fixed version and apply updates accordingly.
In the Linux kernel, the following vulnerability has been resolved: bpf: use kvfree() for replaced sysctl write buffer proc_sys_call_handler()… (CVE-2026-63809)
Description
A memory management vulnerability in the Linux kernel's BPF subsystem was resolved by correcting the deallocation method of a sysctl write buffer in proc_sys_call_handler(). The issue involved improper freeing of memory allocated with kvzalloc(), which may use vmalloc() internally, by using kfree(), potentially causing memory corruption. The fix replaces kfree() with kvfree() to safely handle all allocation types. The vulnerability was confirmed in kernel versions around 7.1-rc4 and 7.1-rc5. No known exploits are reported in the wild.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel vulnerability CVE-2026-63809 involves incorrect memory deallocation in proc_sys_call_handler(), where a buffer allocated with kvzalloc() (which can fall back to vmalloc()) was freed using kfree(), leading to potential memory corruption. The correct function kvfree() was introduced to handle both kmalloc and kvzalloc/vmalloc allocations safely. The bug was identified through experimental memory management analysis and reproduced on kernel version 7.1-rc4 with KASAN and CONFIG_FAILSLAB enabled. Applying the fix prevents kernel oops and memory faults triggered by this improper free operation.
Potential Impact
Improper memory deallocation can cause kernel memory corruption, leading to kernel crashes (oops) and instability. While no exploits are known in the wild, this vulnerability could potentially be leveraged to cause denial of service or other unpredictable kernel behavior due to memory corruption.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to replace kfree() with kvfree() for the affected sysctl write buffer deallocation. Users and administrators should apply the official kernel updates that include this fix. Patch status is not explicitly stated in the provided data; therefore, check the vendor's Linux kernel advisory or mainline kernel repositories for the fixed version and apply updates accordingly.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-vchv-wvp9-hcw9
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-63809"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a5d27ad2a4a8d59891315ba
Added to database: 07/19/2026, 19:38:21 UTC
Last enriched: 07/19/2026, 20:19:40 UTC
Last updated: 07/20/2026, 17:26:47 UTC
Views: 13
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