CVE-2026-74290 net/sched: cls_flow: Dont expose folded kernel pointers
A local attacker with network namespace privileges can recover folded kernel pointers via the flow classifier, leading to information disclosure.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74290?
CVE-2026-74290 is a vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net/sched: cls_flow: Dont expose folded kernel pointers
The flow classifier falls back to addr_fold() for fields that are missing from packet headers. In map mode, userspace controls mask, xor, rshift, addend and divisor, and can observe the resulting classid through class statistics. This allows a tc classifier in a user/network namespace to recover the 32-bit folded value of skb->sk, skb_dst() or skb_nfct().
Align with standard kernel practices for pointer hashing and replace the XOR folding with a keyed siphash (which is cryptographically secure)
Which versions are affected by CVE-2026-74290?
How do I fix CVE-2026-74290?
Apply the vendor's patch.
Is CVE-2026-74290 being exploited?
There is no known exploitation of CVE-2026-74290 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74290, DEBIAN-CVE-2026-74290, GHSA-wfqw-582v-82vh, UBUNTU-CVE-2026-74290.