Look up another CVE · open CVE-2026-64002 in the interactive tracker
CVE-2026-64002
ipv4: free net->ipv4.sysctl_local_reserved_ports after unregister_net_sysctl_table()
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem net/ipv4. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-64002 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixed | 6.1.176-1 | Update the kernel and reboot. Fixed in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
ipv4_sysctl_exit_net() is currently freeing net->ipv4.sysctl_local_reserved_ports too soon. Only after unregister_net_sysctl_table() we can be sure no threads can possibly use the sysctls, including /proc/sys/net/ipv4/ip_local_reserved_ports.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
net/ipv4/sysctl_net_ipv4.c
- What this is
- NETWORKING [GENERAL]MAINTAINERS section matched on net/ · netdev@vger.kernel.org · Maintained
Check it on the machine
grep -wE 'CONFIG_INET|CONFIG_SYSCTL' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
Show whether Debian builds this, per release
Debian builds this code. Every release below compiles the affected file into the kernels it ships.
- bookworm, trixie, forky, sidy
- y
- built into the kernel image on every flavour - only a patch removes it
- Build switches
- CONFIG_INET, CONFIG_SYSCTL
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-07-19 (3 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.13%, higher than 2.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/ipv4
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 3.16 | 5.10.259 | ecf45080a4d3 |
| 3.16 | 5.15.210 | a0ffc6081a8b |
| 3.16 | 6.1.176 | 5b23a2ff379e |
| 3.16 | 6.6.143 | 8e59d4d0dcde |
| 3.16 | 6.12.93 | 6512c57c4638 |
| 3.16 | 6.18.35 | a7f4eefb6e14 |
| 3.16 | 7.0.12 | 155f90be5ee8 |
| 3.16 | 7.1 | 87a1e0fe7776 |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- Exploitation requires local syscalls—network namespace teardown via unshare/setns/put_net, sysctl access to /proc/sys/net/ipv4/ip_local_reserved_ports, and/or local socket bind/connect—not remote packet delivery.
- AC:LAttack complexity, low
- The attacker can control both sides of the race by concurrently tearing down a network namespace while hammering the sysctl or triggering socket port selection in that namespace.
- PR:LPrivileges required, low
- An unprivileged local user can reach this via user namespaces (CAP_SYS_ADMIN within the user_ns for CLONE_NEWNET) and world-writable sysctl access (mode 0644) during namespace destruction.
- UI:NUser interaction, none
- No victim interaction is required beyond the attacker's own concurrent namespace teardown and sysctl or socket activity.
- S:UScope, unchanged
- The UAF corrupts kernel heap memory within the same kernel security domain; it is standard local kernel memory corruption, not a VM/hypervisor boundary escape.
- C:HConfidentiality impact, high
- Freed 8 KiB bitmap memory remains reachable via sysctl reads (find_next_bit) and inet_is_local_reserved_port() (test_bit), enabling heap information disclosure through a use-after-free.
- I:HIntegrity impact, high
- Sysctl writes via proc_do_large_bitmap perform bitmap_copy/bitmap_or into the freed allocation, providing a heap write primitive exploitable for control-flow hijacking.
- A:HAvailability impact, high
- Concurrent access to the freed bitmap can cause kernel oops/panic from invalid memory access, and UAF exploitation inherently threatens kernel availability.