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Linux KernelOperating system · Linux

CVE-2026-43493

CRITICAL · 9.8 CVSS v3.1 Published 2026-05-19
Fix available
A fix is available. Upgrade to 5.10.258 / 5.15.209 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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: crypto: pcrypt - Fix handling of MAY_BACKLOG requests MAY_BACKLOG requests can return EBUSY. Handle them by checking for that value and filtering out EINPROGRESS notifications.

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 · moderate confidence

Linux kernel pcrypt (parallel crypto) module bug fix handling MAY_BACKLOG crypto requests that can return EBUSY. The patch adds proper checking for EBUSY return values and filters out EINPROGRESS notifications to prevent incorrect error handling in the crypto request processing path.

MitigationApply the kernel patch or upgrade to a kernel version containing the pcrypt fix that properly handles MAY_BACKLOG request return values.

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:>= 2.6.34, < 5.10.258>= 5.11, < 5.15.209>= 5.16, < 6.1.175>= 6.2, < 6.6.140>= 6.7, < 6.12.86>= 6.13, < 6.18.27>= 6.19, < 7.0.4

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. Determine your kernel version
    Run 'uname -r' or 'cat /proc/version' to get the running kernel version
    Affected if The kernel version falls within any of these ranges: >= 2.6.34 and < 5.10.258; >= 5.11 and < 5.15.209; >= 5.16 and < 6.1.175; >= 6.2 and < 6.6.140; >= 6.7 and < 6.12.86; >= 6.13 and < 6.18.27; >= 6.19 and < 7.0.4
  2. Check if pcrypt module is loaded
    Run 'lsmod | grep pcrypt' to see if the pcrypt kernel module is currently loaded
    Affected if The pcrypt module is loaded and the kernel version is in an affected range
  3. Verify if pcrypt is compiled into the kernel
    Check kernel config file (typically /boot/config-$(uname -r) or /proc/config.gz) for 'CONFIG_CRYPTO_PCRYPT=y' or 'CONFIG_CRYPTO_PCRYPT=m'
    Affected if pcrypt is enabled in the kernel configuration and the kernel version is in an affected range
  4. Monitor for EBUSY errors in crypto operations
    Check system logs (dmesg, journalctl -k) for 'crypto' or 'pcrypt' related EBUSY error messages, particularly during bulk crypto operations
    Affected if EBUSY errors appear in logs related to crypto operations and kernel version is in an affected range

You are affected if your kernel version is within the affected ranges AND the pcrypt crypto subsystem is actively in use on your system.

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 5.10.258 / 5.15.209 / 6.1.175 or later
Fixed in 5.10.2585.15.2096.1.175
Vendor patch git.kernel.org →
Interim mitigation

Apply the kernel patch or upgrade to a kernel version containing the pcrypt fix that properly handles MAY_BACKLOG request return values.

Recommended fix High confidence

Upgrade to kernel 5.10.258 (for 5.10.x branch), 5.15.209 (for 5.15.x branch), 6.1.175 (for 6.1.x branch), or 6.6.140 (for 6.2+ branches)

  1. Identify the running kernel version using `uname -r`
  2. Download or obtain the kernel source for the applicable fixed version (5.10.258, 5.15.209, 6.1.175, or 6.6.140 depending on your branch)
  3. Apply the patch from commit 1d7f07df450bac3301938fbc4251f2611be4084e which adds EBUSY handling in pcrypt's MAY_BACKLOG request processing, specifically: add a check for the EBUSY return value and filter out EINPROGRESS notifications from the completion path
  4. Rebuild the kernel with the patch applied
  5. Reboot into the patched kernel
Caveat Kernel upgrades may require rebuild of out-of-tree modules; ensure driver compatibility before upgrading

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

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,340
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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-2026-43493 in production — separate from our analysis above.

No notes yet

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