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CVE-2026-72434
netfilter: ipset: make sure gc is properly stopped
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem net/netfilter. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-72434 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 | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixed | 6.12.100-1 | Update the kernel and reboot. Fixed in 6.12.100-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Sashiko noticed that when destroying a set, cancel_delayed_work_sync() was called while gc calls queue_delayed_work() unconditionally which can lead not to properly shutting down the gc.
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/netfilter/ipset/ip_set_hash_gen.h
- What this is
- NETFILTERMAINTAINERS section matched on net/netfilter/ · netfilter-devel@vger.kernel.org · Maintained
Show whether Debian builds this, per release
Not established. This site could not find the build rule for the affected file in the kernel trees Debian ships, so it has no answer about whether Debian compiles this code. Read that as unknown, never as absent.
- bookworm, trixie, forky, sid?
- ?
- not established - no Makefile entry for the affected file
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
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
Signals
- Published
- 2026-08-15 (2 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
- 0.17%, higher than 5.7% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/netfilter
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.6 | 6.12.97 | c940d1b96248 |
| 5.6 | 6.18.40 | 12088da6add5 |
| 5.6 | 7.1.5 | c78bd5195a59 |
| 5.6 | 7.2 | 4a597a87e2e2 |
| 5.4.24 | 0 | 0 |
| 5.5.8 | 0 | 0 |
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 bug is reached only via NFNETLINK ipset destroy/cleanup (IPSET_CMD_DESTROY or netns exit calling cancel_gc), not by processing remote packets; all entry points are local netlink syscalls into net/netfilter/ipset.
- AC:LAttack complexity, low
- An attacker with CAP_NET_ADMIN creates a timeout hash ipset, waits for the workqueue GC to run, then destroys the set; because mtype_gc always re-queues itself at the end of execution, cancel_delayed_work_sync reliably leaves a pending GC after teardown.
- PR:LPrivileges required, low
- All ipset management, including set destroy that calls mtype_cancel_gc, requires CAP_NET_ADMIN checked by netlink_net_capable in nfnetlink; unprivileged users can obtain this in an isolated user+network namespace via unshare -Urn.
- UI:NUser interaction, none
- Exploitation is fully automated through netlink ipset create/destroy commands and does not require any victim user action such as mounting filesystems or opening files.
- S:UScope, unchanged
- The use-after-free corrupts kernel heap memory within the same host kernel security boundary; it does not by itself cross VM, container runtime, or IOMMU isolation boundaries.
- C:HConfidentiality impact, high
- After teardown, the orphaned GC work dereferences freed ip_set and htype structures (including embedded delayed_work), a classic slab UAF that enables heap grooming and arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- UAF on ipset hash control structures and hbucket data allows corrupting freed heap objects and building write primitives for control-flow hijacking and local privilege escalation beyond the caller's namespace.
- A:HAvailability impact, high
- Dereferencing freed set, htype, and hash table memory from the GC workqueue can immediately trigger kernel oopses or panics, and the bug is repeatable on every destroy of a timeout hash ipset.