Cyber Resilience

CVE-2026-6351

Published
16 April 2026
Modified
19 May 2026
CVSS Score v4 8.7
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0059 45th percentile
Risk Priority 45 floored blend · peak EPSS

Summary

CVE-2026-6351 is a high-severity CRLF Injection (CWE-93) vulnerability in Org (inferred from references). Its CVSS base score is 8.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Content Injection (T1659); ranked at the 45th 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 SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-6351 is a CRLF Injection vulnerability (CWE-93) affecting MailGates and MailAudit products developed by Openfind. Published on 2026-04-16, the vulnerability carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N), indicating high severity due to its potential for significant confidentiality impact.

Unauthenticated remote attackers can exploit this vulnerability over the network with low attack complexity, requiring no privileges or user interaction. Successful exploitation allows attackers to read system files on the affected system.

Advisories from TWCERT/CC provide further details on this vulnerability, available at https://www.twcert.org.tw/en/cp-139-10843-9ff91-2.html and https://www.twcert.org.tw/tw/cp-132-10844-1405d-1.html.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

MailGates/MailAudit developed by Openfind has a CRLF Injection vulnerability, allowing unauthenticated remote attackers to exploit this vulnerability to read system files.

CWE(s)
CWE-93

Related Threats

MITRE ATT&CK Enterprise Techniques

T1659 Content Injection Initial Access
Adversaries may gain access and continuously communicate with victims by injecting malicious content into systems through online network traffic.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-49130Shared CWE-93
CVE-2025-6175Shared CWE-93
CVE-2026-43968Shared CWE-93
CVE-2026-44092Shared CWE-93
CVE-2026-12357Shared CWE-93
CVE-2026-39394Shared CWE-93
CVE-2026-35601Shared CWE-93
CVE-2025-41376Shared CWE-93
CVE-2026-33128Shared CWE-93
CVE-2026-21428Shared CWE-93

Affected Assets

Org
—
inferred from references and description; NVD did not file a CPE for this CVE

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)
  • V4.2.4

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match

Input validation directly stops untrusted data containing CRLF sequences from reaching the component that treats CRLF as a delimiter.

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.PS-06 mostly match
prevents

Secure SDLC practices directly require input neutralization and validation to block CRLF injection.

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.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect CRLF flaws but does not itself implement the neutralization.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates input validation and output encoding that directly prevents CRLF injection.

A.8.26 Application security requirements partial match
prevents

Application security requirements include rules for neutralizing special characters such as CRLF in inputs.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles encourage safe handling of untrusted data but do not prescribe specific CRLF controls.

A.8.28 Secure coding partial match
prevents

Secure coding standards explicitly require neutralization of CRLF sequences, fully addressing this weakness.

References