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CVE-2026-53131
netfilter: require Ethernet MAC header before using eth_hdr()
Published 2026-06-25 (4 months ago) by the Linux kernel CNA. Subsystem net/ipv6. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-53131 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-4665-1 · 2026-07-03 · text | 6.1.176-1 | Update the kernel and reboot. DLA-4665-1 shipped the fix on 2026-07-03, 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 | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
`ip6t_eui64`, `xt_mac`, the `bitmap:ip,mac`, `hash:ip,mac`, and `hash:mac` ipset types, and `nf_log_syslog` access `eth_hdr(skb)` after either assuming that the skb is associated with an Ethernet device or checking only that the `ETH_HLEN` bytes at `skb_mac_header(skb)` lie between `skb->head` and `skb->data`. Make these paths first verify that the skb is associated with an Ethernet device, that the MAC header was set, and that it spans at least a full Ethernet header before accessing `eth_hdr(skb)`.
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/ipv6/netfilter/ip6t_eui64.c
net/netfilter/ipset/ip_set_bitmap_ipmac.c
net/netfilter/ipset/ip_set_hash_ipmac.c
net/netfilter/ipset/ip_set_hash_mac.c
net/netfilter/nf_log_syslog.c
net/netfilter/xt_mac.c
- What this is
- NETFILTERMAINTAINERS section matched on net/*/netfilter/ · netfilter-devel@vger.kernel.org · Maintained
- Kernel module
- ip6t_eui64
Check it on the machine
grep -wE 'CONFIG_IP6_NF_MATCH_EUI64|CONFIG_NETFILTER' /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 ip6t_eui64Prints 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_IP6_NF_MATCH_EUI64, CONFIG_NETFILTER
- 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
- 2026-06-25 (4 months ago)source
- CVSS
- 9.4 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.43%, higher than 36.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/ipv6
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.12 | 5.15.210 | 4435888e1bf1 |
| 2.6.12 | 6.1.176 | 063f43361e88 |
| 2.6.12 | 6.6.143 | 726abf975668 |
| 2.6.12 | 6.12.94 | 367abcacc13a |
| 2.6.12 | 6.18.36 | 5d634afb8b83 |
| 2.6.12 | 7.0.13 | cea435ea7e86 |
| 2.6.12 | 7.1 | 62443dc21114 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4671-1 | 2026-07-05 | bullseye 6.1.176-1~deb11u1 | tracker |
| DLA-4665-1 | 2026-07-03 | bookworm 6.1.176-1 | 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:NAttack vector, network
- The vulnerable netfilter match, ipset, and logging paths run while processing packets in receive/netdev hooks. In a reasonable firewall, router, VPN, or tunnel deployment with these rules installed, unauthenticated remote packets can reach the vulnerable code.
- AC:LAttack complexity, low
- No race or difficult timing is required; a packet reaching a vulnerable rule with an invalid, unset, non-Ethernet, or too-short MAC header deterministically drives the bad eth_hdr(skb) access. The needed rule/interface setup is a plausible deployment condition, not an exploit race.
- PR:NPrivileges required, none
- The remote packet sender does not need credentials or local privileges once the affected rule or logger is configured. Although rule installation requires CAP_NET_ADMIN, that is not required for the runtime remote-trigger scenario.
- UI:NUser interaction, none
- Exploitation is triggered by packet processing and does not require a victim user to open a file, mount anything, or perform another action.
- S:UScope, unchanged
- The impact remains within the kernel/network stack security authority. There is no VM, IOMMU, or separate sandbox boundary crossing.
- C:HConfidentiality impact, high
- The flaw causes invalid or out-of-bounds reads from the skb MAC header, and those bytes can be copied into logs/ipset state or influence observable match behavior. Per the required guidance, out-of-bounds reads are scored High when not proven strictly harmless.
- I:LIntegrity impact, low
- The primitive is a read rather than an arbitrary write or control-flow hijack. However, the wrongly read MAC bytes can influence firewall matches and ipset add/delete/test behavior, giving limited integrity impact.
- A:HAvailability impact, high
- Invalid eth_hdr(skb) access can produce slab out-of-bounds/KASAN reports or kernel oops/panic conditions, and packets can be sent repeatedly. Kernel crashes are High availability impact.