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Linux KernelOperating system · Linux

CVE-2026-52989

CRITICAL · 9.8 CVSS v3.1 Published 2026-06-24
Fix available
A fix is available. Upgrade to 5.11 / 5.16 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 8 weeks old

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 · unedited
In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: propagate nvmet_tcp_build_pdu_iovec() errors to its callers Currently, when nvmet_tcp_build_pdu_iovec() detects an out-of-bounds PDU length or offset, it triggers nvmet_tcp_fatal_error(cmd->queue) and returns early. However, because the function returns void, the callers are entirely unaware that a fatal error has occurred and that the cmd->recv_msg.msg_iter was left uninitialized. Callers such as nvmet_tcp_handle_h2c_data_pdu() proceed to blindly overwrite the queue state with queue->rcv_state = NVMET_TCP_RECV_DATA Consequently, the socket receiving loop may attempt to read incoming network data into the uninitialized iterator. Fix this by shifting the error handling responsibility to the callers.

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 analysis · high confidence

In the Linux kernel's NVMe over TCP implementation, the function nvmet_tcp_build_pdu_iovec() detects out-of-bounds PDU length or offset errors but returns void, leaving callers unaware that nvmet_tcp_fatal_error() was triggered. This causes callers like nvmet_tcp_handle_h2c_data_pdu() to proceed with corrupted queue state (rcv_state = NVMET_TCP_RECV_DATA) while the cmd->recv_msg.msg_iter remains uninitialized, leading to potential memory corruption when the socket receiving loop writes to the uninitialized iterator.

MitigationPatch the Linux kernel to a version where nvmet_tcp_build_pdu_iovec() returns error codes instead of void, allowing callers to properly handle fatal errors and avoid operating on uninitialized iterators.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 5.10.250, < 5.11>= 5.15.200, < 5.16>= 6.1.163, < 6.1.175>= 6.6.124, < 6.6.141>= 6.12.70, < 6.12.91>= 6.18.10, < 6.18.33>= 6.19.1, < 7.0.10= 6.19= 7.1

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the running kernel version
    Run `uname -r` or check `/proc/version` to obtain the kernel version string
    Affected if The kernel version is older than the version containing the fix for nvmet_tcp_build_pdu_iovec() returning void instead of error codes
  2. Verify if the nvmet_tcp kernel module is loaded
    Run `lsmod | grep nvmet_tcp` or check `/sys/module/nvmet_tcp` to see if the NVMe over TCP target module is present
    Affected if The module is loaded and NVMe over TCP target functionality is active
  3. Check for active NVMe over TCP target connections
    Inspect `/sys/kernel/config/nvmet/` or use `ls -la /sys/kernel/config/nvmet/targets/` to list configured NVMe over TCP targets
    Affected if Any NVMe over TCP targets are configured and actively handling I/O
  4. Examine the nvmet_tcp_build_pdu_iovec function behavior
    Review kernel source code or use tools like `objdump -d` on the nvmet_tcp.ko module to inspect the function signature
    Affected if The function returns void (no error code) rather than an integer error code suitable for caller handling
  5. Check for PDU handling errors in kernel logs
    Run `dmesg | grep -i nvmet` or check system logs for fatal error messages related to NVMe over TCP PDU processing
    Affected if Frequent nvmet_tcp_fatal_error messages appear without corresponding error handling in caller functions like nvmet_tcp_handle_h2c_data_pdu

The environment is affected if the running kernel contains the vulnerable nvmet_tcp code that returns void from nvmet_tcp_build_pdu_iovec() while triggering fatal errors, AND NVMe over TCP target functionality is actively in use.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

From vendor data
Upgrade available Upgrade to 5.11 / 5.16 / 6.1.175 or later
Fixed in 5.115.166.1.175
Interim mitigation

Patch the Linux kernel to a version where nvmet_tcp_build_pdu_iovec() returns error codes instead of void, allowing callers to properly handle fatal errors and avoid operating on uninitialized iterators.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-52989 in production — separate from our analysis above.

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What this is

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.

What belongs here
  • 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
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