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CVE-2026-72252
netfilter: nft_set_pipapo: don't leak bad clone into future transaction
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-2026-72252 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 | fixedDLA-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| 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
On memory allocation failure the cloned nft_pipapo_match can enter a bad state: - some fields can have their lookup tables resized while others did not - bits might have been toggled - scratch map can be undersized which also means m->bsize_max can be lower than what is required This means that the next insertion in the same batch can trigger out-of-bounds writes. Furthermore, a failure in the first can result in the bad clone to leak into the next transaction because the abort callback is never executed in this case (the upper layer saw an error and no attempt to allocate a transactional request was made). Record a state for the nft_pipapo_match structure: - NEW (pristine clone) - MOD (modified clone with good state) - ERR (potentially bogus content) Then make it so that deletes and insertions fail when the clone entered ERR state. In case the very first insert attempt results in an error, free the clone right away.
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/nft_set_pipapo.c
net/netfilter/nft_set_pipapo.h
- What this is
- NETFILTERMAINTAINERS section matched on net/netfilter/ · netfilter-devel@vger.kernel.org · Maintained
- Kernel module
- nf_tables
Check it on the machine
grep -wE 'CONFIG_NETFILTER|CONFIG_NF_TABLES' /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.
lsmod | grep -w nf_tablesPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.
- bookworm, trixie, forky, sidm
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switches
- CONFIG_NETFILTER, CONFIG_NF_TABLES
- 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
- 2026-08-15 (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 5.8% 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 | 5.15.217 | 0ab7b1802f63 |
| 5.6 | 6.1.184 | cc53703f4855 |
| 5.6 | 6.6.148 | 047e813324ea |
| 5.6 | 6.12.97 | 610e3b73efae |
| 5.6 | 6.18.40 | 02b6b0e892ae |
| 5.6 | 7.1.5 | e74f9680e1b6 |
| 5.6 | 7.2 | 47e65eff5069 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | tracker |
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 the nf_tables netlink control path (NFT_MSG_NEWSETELEM into nft_pipapo_insert); it is not triggered by remote packet handling, so attack vector is Local per kernel nftables guidance.
- AC:LAttack complexity, low
- An attacker can reliably induce the needed allocation failure by crafting wide pipapo interval elements and constraining memory (e.g., memcg limits), then retrying until a partial insert leaves a corrupted clone that the next add reuses.
- PR:LPrivileges required, low
- All nf_tables netlink operations require CAP_NET_ADMIN; on systems with unprivileged user namespaces this capability is obtainable by a normal local user via unshare -Urn, so privileges required are Low rather than High.
- UI:NUser interaction, none
- Exploitation requires only attacker-controlled nftables set element insertions and does not depend on any victim user action such as opening files or mounting filesystems.
- S:UScope, unchanged
- Impact is kernel heap corruption and potential privilege escalation within the same kernel security domain; it does not inherently cross VM, IOMMU, or other sandbox boundaries without separate exploitation.
- C:HConfidentiality impact, high
- A partially updated pipapo clone leaves inconsistent lookup/mapping tables and undersized scratch buffers; subsequent inserts or lookups can perform out-of-bounds heap access that is exploitable for arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- The fix commit explicitly states the corrupted clone can cause out-of-bounds writes on the next insertion, enabling heap corruption that can be leveraged for arbitrary kernel writes and local privilege escalation.
- A:HAvailability impact, high
- Out-of-bounds writes into kernel heap structures commonly cause kernel oops/panic or persistent instability; memory corruption from this bug can crash the system even when full exploitation is not attempted.