Cloudanix VulnDB

CVE-2026-98387

None

CVSS

—

EPSS

0.2%

Published

Oct 14, 2026

CISA due date

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Cloudanix analysis

Schedule a fix SSVC: Track

A coding mistake in the Linux kernel's encryption code for certain IBM mainframe hardware can cause crypto operations to fail or crash the system.

Exploitation
Local Privilege
Attacker needs
Local User
Complexity
Moderate
Impact
Data Exposure
Component
OS kernel
Class
Improper Input Validation
Remediation
Upgrade
Effort
Medium
Patch risk
Low

What it actually does

Missing return code checks on skcipher_walk_virt() in ecb_aes_crypt() and ctr_aes_crypt() allow the walk structure to remain in an undefined state, leading to processing of uninitialized memory or incorrect crypto results on s390.

Why it matters to the business

Cryptographic operations on IBM Z systems may silently fail or crash the kernel, interrupting secure workloads and requiring emergency reboots or rollbacks.

How an attack unfolds

An attacker supplies crafted input that causes skcipher_walk_virt() to fail; the missing check lets subsequent loop iterations dereference or process the uninitialized walk structure, resulting in kernel-level incorrect behavior or memory corruption.

How to fix it

Apply the upstream kernel commit that adds explicit return-code validation after every skcipher_walk_virt() call in aes_s390 before any data processing occurs.

How to confirm the fix worked

Confirm the patched kernel source contains the added error checks; verify no crash or incorrect output occurs when skcipher_walk_virt() is forced to fail in test harnesses.

Typical attack path

  1. Trigger a failure condition in skcipher_walk_virt() via malformed crypto request
  2. Bypass absent return-code check and enter processing loop with undefined walk state
  3. Cause kernel to access uninitialized memory or produce wrong AES output
  4. Escalate to denial of service or information disclosure depending on context

How to detect it

Search kernel logs and crash dumps for skcipher_walk_virt failures, uninitialized memory accesses, or AES crypto oops originating from aes_s390 on s390 platforms.

What your security team should do

  • Prioritize patching all s390 Linux systems within the next maintenance window
  • Monitor kernel logs for skcipher or AES-related oops or warnings on affected hardware
  • Temporarily disable hardware-accelerated AES on s390 if immediate patching is impossible

The record

In the Linux kernel, the following vulnerability has been resolved: s390/crypto: Fix skcipher_walk return code handling in aes_s390 The return codes from skcipher_walk_virt() were not properly checked before entering the processing loops in ecb_aes_crypt() and ctr_aes_crypt(). If skcipher_walk_virt() fails, the walk structure may be in an undefined state, and attempting to process data could lead to incorrect behavior or accessing uninitialized memory. Add proper return code checking to ensure correct handling of the walk initialization and walk advance and eventually return to the caller with that return code.

Affected packages

Ecosystem Package Introduced Fixed