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Linux EUVDEUVD-2026-12804

| CVE-2026-23243 HIGH
Out-of-bounds Write (CWE-787)
2026-03-18 Linux
Buffer Overflow Linux Memory Corruption
7.8
CVSS 3.1 · Vendor: Linux
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Open RDMA/umad device file
  2. Exploit
    Craft MAD header with mismatched RMPP length
  3. Execution
    Send write with negative data_len
  4. Impact
    Trigger out-of-bounds memset in alloc_send_rmpp_list

Vulnerability Assessment

Weakness
CWE
CWE-787
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, write limits
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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Exploitation Conditions

Attacker must have low-privilege local user access to a Linux system with RDMA/umad subsystem enabled. Requires sending a crafted user-space MAD (Management Datagram) packet via ib_umad_write() with mismatched user MAD header size and RMPP header length to trigger negative data_len calculation.
Exploit ScenarioDerived

A local privileged user crafts a malformed MAD (Management Datagram) packet with mismatched header sizes, causing data_len to become negative. This negative value bypasses padding validation, triggering an out-of-bounds memset that corrupts kernel memory and enables privilege escalation or information disclosure.
Act Now Prioritize within 24-48h. Why: Active threat signals + CRITICAL/HIGH severity.
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 18, 2026

A negative integer underflow vulnerability exists in the Linux kernel's RDMA/umad subsystem where the ib_umad_write function fails to validate user-controlled data_len calculations, allowing a mismatch between user MAD header size and RMPP header length to produce negative values. This negative data_len can propagate to ib_create_send_mad() and trigger an out-of-bounds memset in alloc_send_rmpp_list(), causing kernel memory corruption and denial of service. The vulnerability affects Linux kernel versions from 2.6.24 through multiple stable branches (5.10, 5.15, 6.1, 6.6, 6.12, 6.18, 6.19) and requires local access to RDMA user-mode interface to exploit, with patches available across multiple stable kernel versions as referenced in the git commits.

Affected VersionsENISA

Linux 2be8e3ee8efd6f99ce454115c29d09750915021a <9c80d688f402539dfc8f336de1380d6b4ee14316
Linux patch: 0
Linux 2be8e3ee8efd6f99ce454115c29d09750915021a <6eb2919474ca105c5b13d19574e25f0ddcf19ca2
Linux patch: 6.19.4
Linux 2be8e3ee8efd6f99ce454115c29d09750915021a <1371ef6b1ecf3676b8942f5dfb3634fb0648128e
Linux patch: 5.10.252
Linux patch: 6.18.14
Linux patch: 6.6.128
Linux patch: 5.15.202
Linux patch: 6.12.75
Linux 2be8e3ee8efd6f99ce454115c29d09750915021a <205955f29c26330b1dc7fdeadd5bb97c38e26f56
Linux 2be8e3ee8efd6f99ce454115c29d09750915021a <a6a3e4af10993cb9e4b8f0548680aba0ab5f3b0d
Linux 2.6.24
Linux patch: 6.1.165
Linux 2be8e3ee8efd6f99ce454115c29d09750915021a <5551b02fdbfd85a325bb857f3a8f9c9f33397ed2
Linux patch: 7.0-rc1
Linux 2be8e3ee8efd6f99ce454115c29d09750915021a <362e45fd9069ffa1523f9f1633b606ebf72060d7
Linux 2be8e3ee8efd6f99ce454115c29d09750915021a <52ab82cc5cf8ada5c3fb6ffe8f32fdb2fc27a34b

Affected Packages

euvd linux no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

Vendor (Linux) PRIMARY 7.8 HIGH
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SUSE HIGH
Red Hat 7.3 MEDIUM

Primary rating from Vendor (Linux).

CVSS VectorVendor: Linux

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Patch released
Mar 31, 2026 - 21:13 nvd
Patch available
CVE Published
Mar 18, 2026 - 10:05 nvd
HIGH 7.8

DescriptionCVE.org

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

Threat Intelligence Overview

EPSS Score
0.0%
Top 94% exploitable
Threat Intel
2
1 source
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS CISA Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat Yes
Deciding rule
Active threat signals + CRITICAL/HIGH severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation· derived
None
System Exposure· derived
Small
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

49
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +39
PoC: 0
Weaponized: 0
Threat intel: +10
Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Memory Corruption HIGH

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Related Vulnerabilities in Linux Kernel Memory and Bounds Check Flaws

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CVE-2026-23248 HIGH
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CVE-2026-23247 MEDIUM
5.5
CVE-2026-23245 HIGH
7.8
CVE-2026-23244 HIGH
7.1
CVE-2026-23242 HIGH
7.5
CVE-2026-23246 HIGH
8.8

Same weakness CWE-787 – Out-of-bounds Write

View all
CVE-2015-3113 CRITICAL POC
9.8
CVE-2011-2462 CRITICAL POC
9.8
CVE-2012-1889 HIGH POC
8.8
CVE-2010-3333 HIGH POC
7.8
CVE-2014-1761 HIGH POC
7.8
CVE-2009-3129 HIGH POC
7.8
CVE-2021-1732 HIGH POC
7.8
CVE-2013-3346 CRITICAL POC
9.8

Same technique Buffer Overflow

View all
CVE-2017-7269 CRITICAL POC
9.8
CVE-2015-5119 CRITICAL POC
9.8
CVE-2020-0796 CRITICAL POC
10.0
CVE-2019-11043 CRITICAL POC
9.8
CVE-2009-0927 HIGH POC
8.8

Vendor StatusVendor

Debian

linux
Release Status Fixed Version Urgency
bullseye vulnerable 5.10.223-1 -
bullseye (security) vulnerable 5.10.251-1 -
bookworm vulnerable 6.1.159-1 -
bookworm (security) vulnerable 6.1.164-1 -
trixie vulnerable 6.12.73-1 -
trixie (security) vulnerable 6.12.74-2 -
forky fixed 6.19.6-2 -
sid fixed 6.19.8-1 -
(unstable) fixed 6.18.14-1 -

SUSE

Severity: High
Product Status
SUSE Linux Enterprise High Availability Extension 15 SP7 Affected
SUSE Linux Enterprise Module for Basesystem 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Server for SAP Applications 15 SP7 Affected

Threat IntelligenceMISP

CISA Advisories
ICSA-26-209-04 ICSA-26-295-11
Sources: CISA (public domain)

References

Advisories & patches
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-23243 ADVISORY https://ubuntu.com/security/notices/USN-8492-1 ADVISORY https://vuldb.com/?id.351527 REF https://cert-portal.siemens.com/productcert/html/ssa-019113.html REF https://cert-portal.siemens.com/productcert/html/ssa-082556.html REF https://cert-portal.siemens.com/productcert/html/ssa-457936.html REF https://git.kernel.org/stable/c/1371ef6b1ecf3676b8942f5dfb3634fb0648128e REF https://git.kernel.org/stable/c/205955f29c26330b1dc7fdeadd5bb97c38e26f56 REF https://git.kernel.org/stable/c/362e45fd9069ffa1523f9f1633b606ebf72060d7 REF https://git.kernel.org/stable/c/52ab82cc5cf8ada5c3fb6ffe8f32fdb2fc27a34b REF https://git.kernel.org/stable/c/5551b02fdbfd85a325bb857f3a8f9c9f33397ed2 REF https://git.kernel.org/stable/c/6eb2919474ca105c5b13d19574e25f0ddcf19ca2 REF https://git.kernel.org/stable/c/9c80d688f402539dfc8f336de1380d6b4ee14316 REF https://git.kernel.org/stable/c/a6a3e4af10993cb9e4b8f0548680aba0ab5f3b0d

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