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CVE-2026-74669
ipvs: clear IPv4 options after rebasing tunnel ICMP errors
Published 2026-08-22 (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-2026-74669 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 | fixedDSA-6466-1 · 2026-08-25 · text | 6.12.105-1 | Update the kernel and reboot. DSA-6466-1 shipped the fix on 2026-08-25, in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.9-1 | Update the kernel and reboot. Fixed in 7.1.9-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.9-1 | Update the kernel and reboot. Fixed in 7.1.9-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
ip_vs_in_icmp() rebases an skb from the outer ICMP packet to the quoted original request before passing it to icmp_send(). However, IPCB(skb)->opt still describes the outer IPv4 header. A timestamp option in the outer header can therefore leave an offset that points into the quoted transport header after the rebase. __ip_options_echo() treats a byte at that stale location as the option length and copies it into the fixed-size option storage on the __icmp_send() stack, causing a stack out-of-bounds write. Clear the stale option metadata after resetting the network header. Keep the remaining control block fields, including the ingress interface used by the ICMP response path.
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/ipvs/ip_vs_core.c
- What this is
- IPVSMAINTAINERS section matched on net/netfilter/ipvs/ · netdev@vger.kernel.org · Maintained
- Kernel module
- ip_vs
Check it on the machine
grep -wE 'CONFIG_IP_VS|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 ip_vsPrints 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_IP_VS, 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
- 2026-08-22 (2 months ago)source
- CVSS
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.51%, higher than 42.5% 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 |
|---|---|---|
| 3.7 | 5.10.265 | 79ffa99202c9 |
| 3.7 | 5.15.216 | c9413b502047 |
| 3.7 | 6.1.183 | 37c61b374512 |
| 3.7 | 6.6.152 | ed246dd85ebf |
| 3.7 | 6.12.104 | 6f46fc460e93 |
| 3.7 | 6.18.45 | 75eec935444d |
| 3.7 | 7.1.9 | 384b4dae1427 |
| 3.7 | 7.2 | e0ba936287df |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | tracker |
| DSA-6466-1 | 2026-08-25 | trixie 6.12.105-1 | 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 bug is hit when a remote peer sends a crafted ICMP error to an IPVS load balancer; processing occurs in the IPv4 LOCAL_IN/FORWARD netfilter path on received network packets before icmp_send().
- AC:LAttack complexity, low
- An attacker can reliably trigger the path by opening IPVS tunnel traffic, then sending an ICMP error whose outer IPv4 header includes a timestamp option and whose quoted payload aligns bytes at the stale option offset to a large length.
- PR:NPrivileges required, none
- Exploitation requires only the ability to send IPv4/ICMP to the target; the remote attacker needs no local account, capability, or authentication on the victim host.
- UI:NUser interaction, none
- No victim user action is required beyond normal exposure of an IPVS tunnel load balancer to the network; exploitation is driven entirely by attacker-sent packets.
- S:UScope, unchanged
- Impact is confined to kernel memory/stack corruption and privilege boundaries within the host kernel; it does not cross into another security authority such as a VM guest or separate sandbox domain.
- C:HConfidentiality impact, high
- The stale IPCB option metadata drives __ip_options_echo() to memcpy() from attacker-influenced skb bytes into a 40-byte stack buffer, enabling out-of-bounds kernel memory access that can disclose stack/kernel data.
- I:HIntegrity impact, high
- The stack out-of-bounds write in __icmp_send() is attacker-controlled in length and content via crafted quoted headers, providing a standard memory-corruption primitive that can corrupt return addresses and enable arbitrary kernel code execution.
- A:HAvailability impact, high
- Corrupting the __icmp_send() stack frame can immediately panic or oops the kernel during ICMP processing, causing complete loss of availability on the load balancer.