CVE-2026-80588 mptcp: reclaim forward-allocated memory on RX path errors
An attacker can cause unbounded memory growth in the Linux kernel MPTCP receive path, leading to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80588?
CVE-2026-80588 is a high-severity denial of service vulnerability in Linux, published on 26 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
mptcp: reclaim forward-allocated memory on RX path errors
After commit 9db5b3cec4ec ("mptcp: borrow forward memory from subflow"), errors in the receive path prior to queueing skbs into the receive queue do not trigger forward-allocated memory reclaiming.
Prevent forward memory from growing unboundedly in pathological drop scenarios by explicitly reclaiming memory when skbs are dropped.
Which versions are affected by CVE-2026-80588?
How do I fix CVE-2026-80588?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-80588 being exploited?
There is no known exploitation of CVE-2026-80588 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-80588, GHSA-82qc-q32m-354f, UBUNTU-CVE-2026-80588.