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CVE-2026-90062
netfilter: nf_tables: move hardware offload step after building the chain blob
Published 2026-09-17 (31 days 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-2026-90062 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-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Allocate the chain blob before the ruleset offload to reduce chances of entering an inconsistent state where the offloaded ruleset in the nic and the software ruleset differ.
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/nf_tables_api.c
- 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, sid, bookworm · linux-6.12m
- 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
- 2026-09-17 (31 days ago)source
- CVSS
- 7.1 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.16%, higher than 5.3% 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 |
|---|---|---|
| 5.3 | 5.10.270 | 923f824f30fa |
| 5.3 | 5.15.221 | 6e7ad6e69be4 |
| 5.3 | 6.1.188 | 309acbab74e4 |
| 5.3 | 6.6.157 | 79eafe22ab0a |
| 5.3 | 6.12.110 | 52febaf1d311 |
| 5.3 | 6.18.52 | d5497644329d |
| 5.3 | 7.2.6 | 6a7d3b074cfb |
| 5.3 | 7.3 | b1881d362e19 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | 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 trigger is a local NETLINK_NETFILTER batch (NFT_MSG_NEWCHAIN/NFT_MSG_NEWRULE with NFT_CHAIN_HW_OFFLOAD on an NFPROTO_NETDEV ingress chain) delivered via sendmsg into nfnetlink_rcv → nfnetlink_rcv_batch → nf_tables_commit, which called nft_flow_rule_offload_commit before nf_tables_commit_chain_prepare. No remote protocol payload carries this transaction.
- AC:LAttack complexity, low
- The attacker controls the batch so nft_flow_rule_offload_commit can FLOW_BLOCK_BIND/FLOW_CLS_REPLACE first, then nf_tables_commit_chain_prepare's kvmalloc of chain->blob_next (or nf_tables_commit_audit_alloc) fails; they size that blob independently by adding NEWRULE/DELRULE on a large chain in the same commit, or by exhausting kernel memory beforehand. No victim-owned race is required.
- PR:LPrivileges required, low
- nfnetlink_rcv() accepts the batch only after netlink_net_capable(skb, CAP_NET_ADMIN), which tests sock_net(skb->sk)->user_ns. Unprivileged processes obtain that capability with unshare -Urn, and containers already holding NET_ADMIN plus an offload-capable VF/representor can drive nft_chain_offload_support/ndo_setup_tc, so init-namespace root is not required.
- UI:NUser interaction, none
- The attacker opens their own NETLINK_NETFILTER socket and sends the NFT_MSG_BATCH_BEGIN commit that includes the NFT_CHAIN_HW_OFFLOAD chain and rules; no other user must mount media, open a file, or otherwise act.
- S:UScope, unchanged
- Impact is confined to the host kernel and the same netdev ingress flower offload programmed by nft_flow_rule_offload_commit/nft_flow_offload_bind. This does not cross a VM, IOMMU, or other distinct security authority.
- C:NConfidentiality impact, none
- After the failed commit, __nf_tables_abort destroys software nft_rule/nft_base_chain objects while leftover FLOW_CLS_REPLACE state stays in the driver; nft_flow_offload_cmd stores cookie as an opaque (unsigned long)rule id used only for later flower lookup, and this path does not copy kernel memory back to userspace or perform an out-of-bounds read.
- I:HIntegrity impact, high
- nft_flow_rule_offload_commit can complete FLOW_BLOCK_BIND and FLOW_CLS_REPLACE on the NIC, then nf_tables_commit_chain_prepare/nf_tables_commit_audit_alloc failure returns from nf_tables_commit and __nf_tables_abort never calls nft_flow_rule_offload_abort, so aborted ACCEPT/DROP/mirred flower filters remain in hardware after the software chain blob is rolled back.
- A:HAvailability impact, high
- The same leftover FLOW_CLS_REPLACE/FLOW_BLOCK_BIND keeps hardware DROP filters on ingress and leaves flow_block_cb on the driver's list so a later BIND hits flow_block_cb_is_busy; NEWCHAIN abort then kfree's nft_base_chain in nf_tables_chain_destroy while that bind is still live, which can oops on subsequent ndo_setup_tc or netdev teardown.