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CVE-2026-45932
bpf: Fix tcx/netkit detach permissions when prog fd isn't given
Published 2026-05-27 (5 months ago) by the Linux kernel CNA. Subsystem include/linux. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-45932 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 6.18.14-1 | Update the kernel and reboot. Fixed in 6.18.14-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 6.18.14-1 | Update the kernel and reboot. Fixed in 6.18.14-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
This commit fixes a security issue where BPF_PROG_DETACH on tcx or netkit devices could be executed by any user when no program fd was provided, bypassing permission checks. The fix adds a capability check for CAP_NET_ADMIN or CAP_SYS_ADMIN in this case.
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.
include/linux/bpf.h
include/linux/bpf_mprog.h
kernel/bpf/syscall.c
- What this is
- BPF [CORE]MAINTAINERS section matched on include/linux/bpf* · bpf@vger.kernel.org · Maintained
Check it on the machine
grep -wE 'CONFIG_BPF|CONFIG_BPF_SYSCALL' /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_BPF, CONFIG_BPF_SYSCALL
- 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
- 2026-05-27 (5 months ago)source
- CVSS
- 7.3 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.18%, higher than 7.2% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- include/linux
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.6 | 6.18.14 | 4e0772cded10 |
| 6.6 | 6.19.4 | 3f04cc1e5374 |
| 6.6 | 7.0 | ae23bc81ddf7 |
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
- The vulnerability is reached through the local bpf(2) syscall (BPF_PROG_DETACH command); there is no remote network entry point to this code.
- AC:LAttack complexity, low
- An unprivileged user can reliably trigger the detach with a single deterministic syscall; there is no race, timing, or memory-layout dependency, and the only precondition (a tcx/netkit program already attached) is a standard deployment condition.
- PR:LPrivileges required, low
- The entire bug is that no capability is required where CAP_NET_ADMIN/CAP_SYS_ADMIN should be; any basic local unprivileged user can call BPF_PROG_DETACH, which is not gated by unprivileged_bpf_disabled or any default check.
- UI:NUser interaction, none
- Detaching the program requires only the attacker's own syscall; no action by any other user or victim is needed.
- S:UScope, unchanged
- The impact stays within the kernel's own security authority (manipulating network BPF attachment state); no VM/IOMMU/sandbox boundary is crossed.
- C:LConfidentiality impact, low
- Detaching does not read kernel memory directly, but removing a tcx/netkit filtering/isolation program (e.g., a Cilium network policy) can expose traffic or services that were previously confidential, a limited information exposure.
- I:HIntegrity impact, high
- An unprivileged user can make an unauthorized, CAP_NET_ADMIN-level modification to the device's network datapath, and by repeating the call can remove all attached programs, fully subverting the configured network security/policy enforcement.
- A:HAvailability impact, high
- Removing the tcx/netkit datapath program disrupts packet processing for the affected device; in eBPF-datapath deployments this breaks forwarding/NAT/policy and causes loss of network connectivity for the node or its workloads.