CVE-2026-72112 is a structural ownership violation in the io_uring/bpf-ops registration path, not a traditional memory safety bug. During registration, io_install_bpf() unconditionally overwrites ops->priv with the new context, but the teardown path (io_eject_bpf/bpf_io_unreg) traverses only through ops->priv to reach the context it cleans up. The first registered context becomes permanently orphaned: its ctx->loop_step still references the struct_ops trampoline that gets freed when the map is destroyed, but no teardown path reaches it. The trigger is straightforward—register the same ops map twice, pointing ring_fd at different contexts between calls, and the second registration silently orphans the first. The vulnerability is an asymmetric state management failure: ops->priv acts as an ownership sentinel in a code path that fundamentally supports multi-context operation. The proposed fix mirrors an existing guard in hid_bpf_reg() — reject registration when ops->priv is already set — which suggests this is a recognized class of re-registration vulnerability that the struct_ops link path simply missed. However, this fix patches a symptom: the underlying assumption that ops->priv marks a single, stable owner is structurally false for io_uring's asynchronous submission model, where ring contexts can be reconfigured and redirected. The attack surface is constrained by CAP_BPF + CAP_PERFMON requirements, but this isn't a strong security control in environments where BPF is legitimately used—the capability exists precisely because BPF is a high-privilege primitive. The exploit chain requires no races, no info leaks, no timing manipulation—just two sequential registration calls with different ring_fds. This architectural simplicity is the real concern: the fix is trivial and the pattern has recurred across bpf_timer, sock_map, and other struct_ops-adjacent paths. Reviewers should audit other io_uring/bpf-ops registration paths for the same missing state guard, as the class of flaw likely exists elsewhere in code that shipped after hid_bpf_reg() but before this audit.
CVE-2026-72112
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn the Linux kernel, the following vulnerability has been resolved: io_uring/bpf-ops: reject re-registration of an already-bound ops io_install_bpf() only rejects a second registration on the ctx side (ctx->bpf_ops) and sets the per-map back-pointer ops->priv unconditionally. The struct_ops link path never advances a map past BPF_STRUCT_OPS_STATE_READY, so the same io_uring_bpf_ops map can be registered more than once, and bpf_io_reg() re-resolves the target ring via fget(ops->ring_fd) on every call. A caller can therefore point the same ring_fd at a different io_ring_ctx between two BPF_LINK_CREATE calls. The second registration passes the ctx->bpf_ops check (the new ctx has none) and overwrites ops->priv, orphaning the first ctx. Teardown (io_eject_bpf()/bpf_io_unreg()) only reaches a ctx through ops->priv, so the orphaned ctx is never torn down: its ctx->loop_step keeps pointing into the struct_ops trampoline, which is freed once the map is gone. A later io_uring_enter() on the orphaned ring then calls the dangling ctx->loop_step from io_run_loop() -- a use-after-free of freed executable memory, reachable by a task with CAP_BPF + CAP_PERFMON. Reject registration when ops->priv is already set, as hid_bpf_reg() does for its struct_ops.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysisA detailed technical summary for this CVE is being prepared.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped- Locate the io_install_bpf() function in the Linux kernel source code (typically in io_uring/bpf.c or similar io_uring-related files)
- Add a check at the beginning of io_install_bpf() to verify if ops->priv is already set: if (ops->priv) return -EBUSY; or similar error code
- This check should mirror the existing validation in hid_bpf_reg() that rejects registration when ops->priv is already populated
- Recompile the Linux kernel with the modified io_install_bpf() function
- Reboot the system with the patched kernel
Generated from the published advisory — verify against the referenced sources before acting.
There is no version to upgrade to and no patch to apply. Every affected install stays exposed until the vendor ships a fix — or somebody else builds one.
Free. We build fixes in the order the community asks for them — and we’ll tell you the moment this one lands.
We develop and verify an original fix where the vendor hasn’t, from $4,900. Deployed to your staging first — never straight to production.
Scope it with usSee what else the community needs solved on the solutions-needed board.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-72112 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesCVE-2026-72112 is a structural ownership violation in the io_uring/bpf-ops registration path, not a traditional memory safety bug. During registration, io_install_bpf() unconditionally overwrites ops->priv with the new context, but the teardown path (io_eject_bpf/bpf_io_unreg) traverses only through ops->priv to reach the context it cleans up. The first registered context becomes permanently orphaned: its ctx->loop_step still references the struct_ops trampoline that gets freed when the map is destroyed, but no teardown path reaches it. The trigger is straightforward—register the same ops map twice, pointing ring_fd at different contexts between calls, and the second registration silently orphans the first. The vulnerability is an asymmetric state management failure: ops->priv acts as an ownership sentinel in a code path that fundamentally supports multi-context operation. The proposed fix mirrors an existing guard in hid_bpf_reg() — reject registration when ops->priv is already set — which suggests this is a recognized class of re-registration vulnerability that the struct_ops link path simply missed. However, this fix patches a symptom: the underlying assumption that ops->priv marks a single, stable owner is structurally false for io_uring's asynchronous submission model, where ring contexts can be reconfigured and redirected. The attack surface is constrained by CAP_BPF + CAP_PERFMON requirements, but this isn't a strong security control in environments where BPF is legitimately used—the capability exists precisely because BPF is a high-privilege primitive. The exploit chain requires no races, no info leaks, no timing manipulation—just two sequential registration calls with different ring_fds. This architectural simplicity is the real concern: the fix is trivial and the pattern has recurred across bpf_timer, sock_map, and other struct_ops-adjacent paths. Reviewers should audit other io_uring/bpf-ops registration paths for the same missing state guard, as the class of flaw likely exists elsewhere in code that shipped after hid_bpf_reg() but before this audit.
Practitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-72112 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data