Security Resilience

CVE-2026-88647

Published
08 October 2026
Modified
10 October 2026
CVSS Score v3.1 9.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS Score 0.0021 11th percentile
Risk Priority 65 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-88647 is a critical-severity Improper Validation of Certificate with Host Mismatch (CWE-297) vulnerability. Its CVSS base score is 9.1 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Adversary-in-the-Middle (T1557); ranked at the 11th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-8 (Security and Privacy Engineering Principles) and SC-23 (Session Authenticity) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A07:2025 Authentication Failures

EU & UK References

Vulnerability Data

A hostname verification bypass in GnuTLS v3.8.13 allows attackers to circumvent the Common Name fallback mechanism and eavesdrop on communications via a crafted certificate.

CWE(s)
CWE-297

Related Threats

MITRE ATT&CK Enterprise Techniques

T1557 Adversary-in-the-Middle Credential Access
Adversaries may attempt to position themselves between two or more networked devices using an adversary-in-the-middle (AiTM) technique to support follow-on behaviors such as [Network Sniffing](https://attack.
attack.mitre.org →
T1557.001 Name Resolution Poisoning and SMB Relay Credential Access
By responding to LLMNR/NBT-NS/mDNS network traffic, adversaries may spoof an authoritative source for name resolution to force communication with an adversary controlled system.
attack.mitre.org →
T1557.002 ARP Cache Poisoning Credential Access
Adversaries may poison Address Resolution Protocol (ARP) caches to position themselves between the communication of two or more networked devices.
attack.mitre.org →
T1557.003 DHCP Spoofing Credential Access
Adversaries may redirect network traffic to adversary-owned systems by spoofing Dynamic Host Configuration Protocol (DHCP) traffic and acting as a malicious DHCP server on the victim network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-46408Shared CWE-297
CVE-2026-54275Shared CWE-297
CVE-2026-19553Shared CWE-297
CVE-2025-3501Shared CWE-297
CVE-2025-59060Shared CWE-297
CVE-2024-2466Shared CWE-297
CVE-2025-42921Shared CWE-297
CVE-2026-15925Shared CWE-297
CVE-2026-35563Shared CWE-297
CVE-2026-48145Shared CWE-297

Affected Assets

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V17.2.8

Mitigating Controls (NIST 800-53 r5) AI

SA-8 Security and Privacy Engineering Principles partial match

Security engineering principles require correct implementation of certificate validation (including hostname matching) when cryptography is used.

SC-23 Session Authenticity partial match

Protecting session authenticity structurally requires proper certificate validation to bind the presented certificate to the intended host.

SC-8 Transmission Confidentiality and Integrity partial match

Requiring confidentiality and integrity of transmitted data necessitates correct TLS certificate validation with host-name checking.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-03 partial match
blocks

Server/service authentication via certificates directly requires correct host validation.

PR.DS-02 partial match
blocks

Protecting data-in-transit integrity depends on proper certificate validation to prevent MITM.

PR.PS-06 partial match
blocks

Secure development practices include coding correct certificate validation logic.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.7.2 Physical entry partial match
removes
A.8.19 Installation of software on operational systems partial match
removes
A.8.20 Networks security partial match
degrades

Network security controls include certificate validation and host-name verification to prevent man-in-the-middle attacks.

A.8.21 Security of network services partial match
degrades

Security of network services requires proper TLS configuration and certificate validation for service endpoints.

A.8.24 Use of cryptography partial match
blocks

A.8.24 mandates proper use of cryptography (algorithms, key management, certificates for protection) but does not address or stop exploitation of a certificate-hostname validation flaw in the product's TLS handshake logic

A.8.26 Application security requirements partial match
blocks

Application security requirements include secure communication and certificate validation for external services.

References