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Linux KernelOperating system · Linux

CVE-2026-23243

HIGH · 7.8 CVSS v3.1 Published 2026-03-18
Fix available
A fix is available. Upgrade to 5.10.252 / 5.15.202 or later.
See remediation →
80/100
Remediation priority · High
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: RDMA/umad: Reject negative data_len in ib_umad_write ib_umad_write computes data_len from user-controlled count and the MAD header sizes. With a mismatched user MAD header size and RMPP header length, data_len can become negative and reach ib_create_send_mad(). This can make the padding calculation exceed the segment size and trigger an out-of-bounds memset in alloc_send_rmpp_list(). Add an explicit check to reject negative data_len before creating the send buffer. KASAN splat: [ 211.363464] BUG: KASAN: slab-out-of-bounds in ib_create_send_mad+0xa01/0x11b0 [ 211.364077] Write of size 220 at addr ffff88800c3fa1f8 by task spray_thread/102 [ 211.365867] ib_create_send_mad+0xa01/0x11b0 [ 211.365887] ib_umad_write+0x853/0x1c80

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
How this class of weakness works · CWE-787

The program writes past the bounds of a buffer, overwriting adjacent memory an attacker can turn to their advantage. Crafted input can overwrite control data and redirect execution. Remediation is validating every index and length before a write, plus modern memory-safety mitigations.

General guidance for the out-of-bounds write class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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:>= 2.6.24.1, < 5.10.252>= 5.11, < 5.15.202>= 5.16, < 6.1.165>= 6.2, < 6.6.128>= 6.7, < 6.12.75>= 6.13, < 6.18.14>= 6.19, < 6.19.4= 2.6.24

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
Upgrade available Upgrade to 5.10.252 / 5.15.202 / 6.1.165 or later
Fixed in 5.10.2525.15.2026.1.165
Vendor patch git.kernel.org →
Recommended fix High confidence

Upgrade to the first fixed release in your kernel branch: 5.10.252, 5.15.202, 6.1.165, or 6.6.128 depending on current branch

  1. Identify the current running kernel version using 'uname -r'
  2. Determine which affected version range applies to your current kernel
  3. Upgrade to the first fixed version in your branch: for 5.10.x upgrade to >=5.10.252, for 5.11-5.15.x upgrade to >=5.15.202, for 5.16-6.1.x upgrade to >=6.1.165, for 6.2-6.6.x upgrade to >=6.6.128
  4. Use your distribution's package manager to install the updated kernel (e.g., apt-get update && apt-get install linux-image-<version> for Debian/Ubuntu, or yum/dnf update for RHEL/CentOS)
  5. Reboot the system to load the patched kernel
  6. Verify the fix is applied by checking the kernel version and confirming the commit 1371ef6b1ecf is included
Caveat Kernel upgrades may require driver recompilation or system reboot; ensure compatibility of custom modules and critical applications with the new kernel version before production deployment

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

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,200. Get the upgrade done

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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-2026-23243 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
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