dbcve.org
Linux KernelOperating system · Linux

CVE-2026-53014

MEDIUM · 5.5 CVSS v3.1 Published 2026-06-24
Fix available
A fix is available. Upgrade to 6.12.91 / 6.18.33 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available 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: net/sched: act_mirred: fix wrong device for mac_header_xmit check in tcf_blockcast_redir In tcf_blockcast_redir(), when iterating block ports to redirect packets to multiple devices, the mac_header_xmit flag is queried from the wrong device. The loop sends to dev_prev but queries dev_is_mac_header_xmit(dev) — which is the NEXT device in the iteration, not the one being sent to. This causes tcf_mirred_to_dev() to make incorrect decisions about whether to push or pull the MAC header. When the block contains mixed device types (e.g., an ethernet veth and a tunnel device), intermediate devices get the wrong mac_header_xmit flag, leading to skb header corruption. In the worst case, skb_push_rcsum with an incorrect mac_len can exhaust headroom and panic. The last device in the loop is handled correctly (line 365-366 uses dev_is_mac_header_xmit(dev_prev)), confirming this is a copy-paste oversight for the intermediate devices. Fix by using dev_prev instead of dev for the mac_header_xmit query, consistent with the device actually being sent to.

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 net/sched act_mirred module, the tcf_blockcast_redir() function incorrectly queries the mac_header_xmit flag from the wrong device during packet redirection to multiple devices. The code uses 'dev' (the next device in iteration) instead of 'dev_prev' (the actual device being sent to), causing tcf_mirred_to_dev() to make incorrect MAC header push/pull decisions. When the block contains mixed device types (e.g., ethernet veth and tunnel device), this leads to skb header corruption and potential kernel panic via skb_push_rcsum with incorrect mac_len.

MitigationApply the kernel patch to correct the mac_header_xmit query from 'dev' to 'dev_prev' in tcf_blockcast_redir(), then rebuild and reboot the kernel. Avoid using mixed device types in act_mirred block configurations until the fix is applied.

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:>= 6.8, < 6.12.91>= 6.13, < 6.18.33>= 6.19, < 7.0.10

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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. Determine running kernel version
    Run 'uname -r' or check /proc/version to get the kernel version string
    Affected if The kernel version falls within any of these ranges: >= 6.8 and < 6.12.91; >= 6.13 and < 6.18.33; >= 6.19 and < 7.0.10
  2. Verify act_mirred module is in use
    Run 'lsmod | grep act_mirred' to check if the module is loaded, or run 'tc filter show' to see if any tc rules with 'mirred' action exist
    Affected if The act_mirred module is loaded or any tc filter rules using the mirred action are configured on the system
  3. Identify mirred configurations with multiple devices
    Run 'tc filter show' and inspect any rules containing 'mirred' action. Look for 'block' configurations with multiple devices by examining 'tc qdisc show' and checking for shared block handlers
    Affected if There are tc mirred rules that redirect packets to multiple devices within a single block configuration
  4. Check for mixed device types in mirred blocks
    For each mirred block configuration found, identify the device types involved (e.g., veth, tunnel devices like vxlan, geneve) using 'ip link show' and compare device types within the same block
    Affected if The block contains or references a mix of different device types (e.g., ethernet veth paired with tunnel devices like vxlan, gre, geneve)
  5. Inspect tcf_blockcast_redir source for the bug
    If the kernel source is available, examine net/sched/act_mirred.c and locate the tcf_blockcast_redir() function. Verify if it queries mac_header_xmit from 'dev' instead of 'dev_prev'
    Affected if The source code shows mac_header_xmit being queried from 'dev' rather than 'dev_prev' in the tcf_blockcast_redir function

You are likely affected if your kernel version is in the affected ranges AND you have tc mirred rules with block-based redirection involving mixed device types.

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.

dbcve · scoped
Upgrade available Upgrade to 6.12.91 / 6.18.33 / 7.0.10 or later
Fixed in 6.12.916.18.337.0.10
Vendor patch git.kernel.org →
Interim mitigation

Apply the kernel patch to correct the mac_header_xmit query from 'dev' to 'dev_prev' in tcf_blockcast_redir(), then rebuild and reboot the kernel. Avoid using mixed device types in act_mirred block configurations until the fix is applied.

Recommended fix High confidence

Linux Kernel 6.12.91+ / 6.18.33+ / 7.0.10+ (depending on your current branch)

  1. 1. Identify the current running kernel version using 'uname -r' or 'cat /proc/version'
  2. 2. Determine which version branch your kernel belongs to (6.8-6.12.x, 6.13-6.18.x, or 6.19-7.0.x) based on the affected versions list
  3. 3. For 6.8-6.12.x branch: upgrade to kernel version 6.12.91 or later
  4. 4. For 6.13-6.18.x branch: upgrade to kernel version 6.18.33 or later
  5. 5. For 6.19-7.0.x branch: upgrade to kernel version 7.0.10 or later
  6. 6. Use your distribution's package manager to install the new kernel (e.g., 'apt-get install linux-image-<version>' for Debian/Ubuntu, 'yum install kernel-<version>' for RHEL/CentOS, or 'pacman -S linux<version>' for Arch)
  7. 7. Reboot the system to load the new kernel
  8. 8. Verify the fix is applied by checking the kernel version with 'uname -r' and confirming it matches one of the fixed versions
Caveat Kernel upgrades may require matching kernel headers and modules; ensure all system components are compatible with the new kernel version before rebooting

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,380
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,808.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-53014 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2026-53014 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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
  • No spam, self-promotion, credentials, or personal data