CVE-2026-93105 esp: do not unref managed frag pages in esp_ssg_unref()
A missing guard in the Linux kernel ESP implementation causes premature page freeing for managed fragments, potentially leading to use-after-free and code execution.
- 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-2026-93105?
CVE-2026-93105 is a high-severity use after free vulnerability in Linux, published on 17 Sep 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:
esp: do not unref managed frag pages in esp_ssg_unref()
esp_ssg_unref() releases the page references held on the source scatterlist after the AEAD operation completes. It calls skb_page_unref() on every frag page for an out-of-place transform (req->src != req->dst), and in the error path of esp_output_tail() (already_unref == true) on the request's own scatterlist.
This is wrong when the skb carries managed frags (SKBFL_MANAGED_FRAG_REFS). Managed frags are owned by a zerocopy ubuf and the skb does not hold a per-frag page reference; io_uring SEND_ZC with a registered buffer attaches the bvec pages this way via io_sg_from_iter(). The rest of the stack honours this invariant: skb_release_data() skips the per-frag unref when SKBFL_MANAGED_FRAG_REFS is set, and skb_zcopy_managed() is the guard used at the other unref sites.
esp_ssg_unref() is missing that guard, so for a managed-frag skb it drops a page reference the skb never acquired. This can underflow the page reference count and free a page that is still in use.
Guard the function with skb_zcopy_managed() so both unref paths are skipped for managed-frag skbs, matching skb_release_data().
Which versions are affected by CVE-2026-93105?
How do I fix CVE-2026-93105?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-93105 being exploited?
There is no known exploitation of CVE-2026-93105 in the wild and no public exploit code.
Sources
Also known as AZL-102042, BELL-CVE-2026-93105, DEBIAN-CVE-2026-93105, GHSA-m483-33mw-4p7w, UBUNTU-CVE-2026-93105.