Cyber Resilience

CVE-2023-38998

Open Redirect in Opnsense ≤ 23.7

Public PoCOpen Redirect
Published
09 August 2023
Modified
21 November 2024
Patch / advisory
View advisory
CVSS Score v3.1 6.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS Score 0.0059 45th percentile
Risk Priority 47 floored blend · peak EPSS

Summary

CVE-2023-38998 is a medium-severity Open Redirect (CWE-601) vulnerability in Opnsense Opnsense. Its CVSS base score is 6.1 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Phishing (T1566); ranked at the 45th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access Control

EU & UK References

Vulnerability Data

An open redirect in the Login page of OPNsense Community Edition before 23.7 and Business Edition before 23.4.2 allows attackers to redirect a victim user to an arbitrary web site via a crafted URL.

CWE(s)
CWE-601

Related Threats

MITRE ATT&CK Enterprise Techniques

T1566 Phishing Initial Access
Adversaries may send phishing messages to gain access to victim systems.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-38999Same product: Opnsense Opnsense
CVE-2023-27152Same product: Opnsense Opnsense
CVE-2026-30868Same product: Opnsense Opnsense
CVE-2026-44195Same product: Opnsense Opnsense
CVE-2026-45158Same product: Opnsense Opnsense
CVE-2026-34578Same product: Opnsense Opnsense
CVE-2023-39004Same product: Opnsense Opnsense
CVE-2025-50989Same product: Opnsense Opnsense
CVE-2023-39002Same product: Opnsense Opnsense
CVE-2023-39006Same product: Opnsense Opnsense

Affected Assets

opnsense
opnsense
≤ 23.7

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)
  • V3.7.2

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

AT-2 Literacy Training and Awareness
addresses: CWE-601

Security awareness includes verifying URLs and avoiding untrusted redirects that lead to malicious sites.

SI-10 Information Input Validation
addresses: CWE-601

Validates redirect targets and URLs to ensure they conform to allowed destinations.

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 validation and untrusted-redirect controls that prevent CWE-601.

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.8.23 Web filtering partial match
mitigates

Preventing access to attacker-controlled or malicious sites stops users from being redirected to untrusted locations via open-redirect or phishing links.

References