Medium · published June 25, 2026
In the Linux kernel, the following vulnerability has been resolved:
netfilter: synproxy: add mutex to guard hook reference counting
As the synproxy infrastructure register netfilter hooks on-demand when a
user adds the first iptables target or nftables expression, if done
concurrently they can race each other.
Introduce a mutex to serialize the refcount control blocks access from
both frontends. While a per namespace mutex might be more efficient, it
is not needed for target/expression like SYNPROXY.
| Product | Versions | Fixed in |
|---|---|---|
| linux/linux_kernel | ≥ 5.3, < 5.10.259 | 5.10.259 |
| linux/linux_kernel | ≥ 5.11, < 5.15.210 | 5.15.210 |
| linux/linux_kernel | ≥ 5.16, < 6.1.176 | 6.1.176 |
| linux/linux_kernel | ≥ 6.2, < 6.6.143 | 6.6.143 |
| linux/linux_kernel | ≥ 6.7, < 6.12.94 | 6.12.94 |
| linux/linux_kernel | ≥ 6.13, < 6.18.36 | 6.18.36 |
| linux/linux_kernel | ≥ 6.19, < 7.0.13 | 7.0.13 |
| linux/linux_kernel | all versions | — |
| linux/linux_kernel | all versions | — |
| linux/linux_kernel | all versions | — |
| linux/linux_kernel | all versions | — |
| linux/linux_kernel | all versions | — |
| linux/linux_kernel | all versions | — |