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Linux KernelOperating system · Linux

CVE-2026-43284

HIGH · 8.8 CVSS v3.1 Published 2026-05-08
Fix available
A fix is available. Upgrade to 5.10.255 / 5.15.205 or later.
See remediation →
90/100
Remediation priority · Urgent
High EPSS Public exploit Zero-click Patch available

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: xfrm: esp: avoid in-place decrypt on shared skb frags MSG_SPLICE_PAGES can attach pages from a pipe directly to an skb. TCP marks such skbs with SKBFL_SHARED_FRAG after skb_splice_from_iter(), so later paths that may modify packet data can first make a private copy. The IPv4/IPv6 datagram append paths did not set this flag when splicing pages into UDP skbs. That leaves an ESP-in-UDP packet made from shared pipe pages looking like an ordinary uncloned nonlinear skb. ESP input then takes the no-COW fast path for uncloned skbs without a frag_list and decrypts in place over data that is not owned privately by the skb. Mark IPv4/IPv6 datagram splice frags with SKBFL_SHARED_FRAG, matching TCP. Also make ESP input fall back to skb_cow_data() when the flag is present, so ESP does not decrypt externally backed frags in place. Private nonlinear skb frags still use the existing fast path. This intentionally does not change ESP output. In esp_output_head(), the path that appends the ESP trailer to existing skb tailroom without calling skb_cow_data() is not reachable for nonlinear skbs: skb_tailroom() returns zero when skb->data_len is nonzero, while ESP tailen is positive. Thus ESP output will either use the separate destination-frag path or fall back to skb_cow_data().

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

A race condition in Linux kernel's ESP (IPsec) input path allows in-place decryption on shared skb frags. When UDP datagrams receive spliced pipe pages, they don't mark them with SKBFL_SHARED_FRAG (unlike TCP), causing ESP to use a fast no-COW decryption path on data it doesn't privately own, leading to potential data corruption or information disclosure.

MitigationApply the kernel patch that marks IPv4/IPv6 datagram splice frags with SKBFL_SHARED_FRAG and makes ESP input fall back to skb_cow_data() when this flag is present.

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:>= 4.11, < 5.10.255>= 5.12, < 5.15.205>= 5.16, < 6.1.171>= 6.2, < 6.6.138>= 6.7, < 6.12.87>= 6.13, < 6.18.28>= 7.0, < 7.0.5

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
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/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. Check the running kernel version
    Run `uname -r` or `cat /proc/version` to obtain the kernel version
    Affected if The version falls within any of the affected ranges: >= 4.11 and < 5.10.255, >= 5.12 and < 5.15.205, >= 5.16 and < 6.1.171, >= 6.2 and < 6.6.138, >= 6.7 and < 6.12.87, >= 6.13 and < 6.18.28, or >= 7.0 and < 7.0.5
  2. Verify XFRM/ESP kernel support is enabled
    Check if the kernel has XFRM and ESP support by running `grep -i xfrm /proc/config.gz 2>/dev/null || lsmod | grep xfrm`
    Affected if XFRM and ESP modules are loaded or compiled in, enabling IPsec functionality
  3. Identify active ESP-in-UDP tunnels
    Run `ip xfrm state` and `ip xfrm policy` to list active IPsec security associations and policies, then check `netstat -anu | grep -E ':(4500|500)\s'` for UDP encapsulation
    Affected if ESP-in-UDP tunnels (typically ports 4500 or 500) are active, meaning UDP-encapsulated ESP traffic is being processed
  4. Check for splice operations with shared pages
    Inspect running services or applications that use splice() or sendpage() with shared memory pages alongside ESP-in-UDP, as this combination triggers the vulnerable code path
    Affected if The system both uses ESP-in-UDP and performs datagram splice operations with potentially shared pipe pages

A system is affected if it runs a kernel version within the affected ranges AND processes ESP-in-UDP traffic while using splice operations that involve shared pages, as only this combination triggers the unsafe decryption path.

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 5.10.255 / 5.15.205 / 6.1.171 or later
Fixed in 5.10.2555.15.2056.1.171
Vendor patch git.kernel.org →
Interim mitigation

Apply the kernel patch that marks IPv4/IPv6 datagram splice frags with SKBFL_SHARED_FRAG and makes ESP input fall back to skb_cow_data() when this flag is present.

Recommended fix High confidence

Upgrade to Linux kernel >= 5.10.255, >= 5.15.205, >= 6.1.171, or >= 6.6.138 (depending on which major version line you are on)

  1. Identify the currently running Linux kernel version using `uname -r`
  2. Determine which version range your current kernel falls into from the affected ranges: >= 4.11 and < 5.10.255, >= 5.12 and < 5.15.205, >= 5.16 and < 6.1.171, or >= 6.2 and < 6.6.138
  3. Plan downtime for kernel upgrade as this requires a system reboot
  4. Upgrade the Linux kernel to a version >= 5.10.255 (for 5.10.x line), >= 5.15.205 (for 5.15.x line), >= 6.1.171 (for 6.1.x line), or >= 6.6.138 (for 6.2+ lines)
  5. For Debian/Ubuntu: `apt-get update && apt-get install linux-image-<version>` and reboot
  6. For RHEL/CentOS: `yum update kernel` and reboot
  7. For Arch Linux: `pacman -Syu` and reboot
  8. For Fedora: `dnf update kernel` and reboot
Caveat Kernel upgrades may require updated drivers or modules; ensure compatibility with your system configuration before upgrading production systems

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 / QA3.0 h
15.0 hours of engineering $2,560
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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-2026-43284 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
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  • Version or environment caveats, and links to real fixes
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