SB20261007210 - Multiple vulnerabilities in IBM PowerVC
Published: October 7, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 2 vulnerabilities.
1) Input validation error (CVE-ID: CVE-2026-75595)
CWE-ID: CWE-20 - Improper input validation
CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to bypass mTLS requirements.
The vulnerability exists due to an incorrect offset check in io.netty.handler.ssl.SslClientHelloHandler#decode when parsing a fragmented TLS ClientHello whose handshake header spans multiple records. A remote attacker can send a specially crafted fragmented TLS ClientHello to bypass mTLS requirements.
This issue affects deployments where per-SNI SslContext selection is the only mTLS gate, the default SslContext is permissive, and no secondary peer-certificate verification exists at the application layer.
2) Inefficient Algorithmic Complexity (CVE-ID: CVE-2026-75596)
CWE-ID: CWE-407 - Inefficient Algorithmic Complexity
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to inefficient algorithmic complexity in the default SNI parsing path when processing fragmented TLS ClientHello records before handshake completion. A remote attacker can send many tiny handshake fragments that advertise a large ClientHello length to cause a denial of service.
The issue can degrade or stall TLS connection handling for other clients on the affected event loop.
Remediation
Install update from vendor's website.