CVE-2026-93105: esp: do not unref managed frag pages in esp_ssg_unref()

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-17 · updated 2026-10-30

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().

Affected products

Linux: 4.11 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux 7.3. Check the vendor advisory for mitigations.

References

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