esp: do not unref managed frag pages in esp_ssg_unref()
CVE-2026-93105 · published 17 Sept 2026
How serious is it
- Severity: high, CVSS score 7.8 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-93105?
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Who is affected
- Linux Linux: cac2661c53f35cbe651bef9b07026a5a05ab8ce0 to < 201bdf10ae92e7cbd524adf8c0323e2a963d5fd7, cac2661c53f35cbe651bef9b07026a5a05ab8ce0 to < 3ec55f0c8a6a543cf660584d1346e11f6311ee59, cac2661c53f35cbe651bef9b07026a5a05ab8ce0 to < 1ad6456898f6e6cf58be83bdb607acb1119a9cd1, cac2661c53f35cbe651bef9b07026a5a05ab8ce0 to < 26b6b14c7a0368e317a1e9fb5144ebe6f8d495cf
- Linux Linux: 4.11
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
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().
Check your whole app
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References
- git.kernel.org/stable/c/201bdf10ae92e7cbd524adf8c0323e2a963d5fd7
- git.kernel.org/stable/c/3ec55f0c8a6a543cf660584d1346e11f6311ee59
- git.kernel.org/stable/c/1ad6456898f6e6cf58be83bdb607acb1119a9cd1
- git.kernel.org/stable/c/26b6b14c7a0368e317a1e9fb5144ebe6f8d495cf
- git.kernel.org/stable/c/21697720ff43b8dfa25b8e8d9ca7f56f4597fc80
Merged from CVE List. Last updated 26 Oct 2026. All vulnerabilities · RSS · JSON