Cyber Resilience

CVE-2026-45692

Access Control in Caddyserver Caddy 2.4.0 – 2.11.3

Public PoCAccess Control
Published
23 June 2026
Modified
26 June 2026
Patch / advisory
CVSS Score v3.1 5.4
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
EPSS Score 0.0017 6th percentile
Risk Priority 41 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-2026-45692 is a medium-severity Partial String Comparison (CWE-187) vulnerability in Caddyserver Caddy. Its CVSS base score is 5.4 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 6th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to AC-24 (Access Control Decisions) and AC-25 (Reference Monitor) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

EU & UK References

No EU or UK CSIRT advisories indexed for this CVE.

Vulnerability Data

Caddy is an extensible server platform that uses TLS by default. From 2.4.0 until 2.11.3, the authorization layer and the /config traversal layer do not agree on what object the path refers to. In this case, a path authorized for…

more

one config object is accepted, but then resolves to a different config object during traversal. This happens because the authorization layer uses string prefix matching and the /config traversal layer parses array indices numerically using strconv.Atoi(). This vulnerability is fixed in 2.11.3.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
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.
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
T1548 Abuse Elevation Control Mechanism Privilege Escalation
Adversaries may circumvent mechanisms designed to control privilege elevation to gain higher-level permissions.
T1548.002 Bypass User Account Control Privilege Escalation
Adversaries may bypass UAC mechanisms to elevate process privileges on system.
T1548.003 Sudo and Sudo Caching Privilege Escalation
Adversaries may perform sudo caching and/or use the sudoers file to elevate privileges.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-27585Same product: Caddyserver Caddy
CVE-2026-27590Same product: Caddyserver Caddy
CVE-2026-45135Same product: Caddyserver Caddy
CVE-2026-27589Same product: Caddyserver Caddy
CVE-2026-27588Same product: Caddyserver Caddy
CVE-2026-27587Same product: Caddyserver Caddy
CVE-2026-52846Same product: Caddyserver Caddy
CVE-2026-52845Same product: Caddyserver Caddy
CVE-2026-30851Same product: Caddyserver Caddy
CVE-2026-30852Same product: Caddyserver Caddy

Affected Assets

caddyserver
caddy
2.4.0 — 2.11.3

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 5 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V10.4.1

Mitigating Controls (NIST 800-53 r5) AI

AC-3 directly requires correct enforcement of authorization decisions on every access request, structurally preventing incorrect checks.

AC-24 ensures access-control decisions are made and applied consistently, reducing the chance of an incorrect authorization result.

A reference monitor that is always invoked and tamper-proof forces every authorization decision through a verified, correct path.

Developer testing and evaluation can discover incomplete string comparisons through targeted test cases.

Least-privilege assignments shrink the set of authorizations that must be checked correctly, limiting exposure to flawed checks.

Security engineering principles include correct and complete comparison logic to avoid flawed decision points.

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-05 mostly match
prevents

Defining, enforcing, and reviewing access authorizations and least privilege directly prevents incorrect authorization checks.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly prevent unsafe string comparisons by enforcing proper API usage and testing.

ID.RA-01 partial match
prevents

Vulnerability identification processes can discover partial-comparison flaws during code or binary analysis.

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.

finds

Security testing can detect and prevent partial string comparison flaws before deployment.

prevents

Requiring consistency between access rights and classification plus formal approval steps ensures that the authorization logic correctly distinguishes between entities that should and should not be granted access.

prevents

Enforcing policy-driven approval and role-change reviews stops incorrect or stale authorization decisions from remaining in effect after job changes or terminations.

prevents

Secure development lifecycle practices can include requirements to avoid partial string comparisons in authentication or validation logic.

prevents

Application security requirements can mandate full, exact comparisons for sensitive operations.

degrades

Secure system architecture principles discourage unsafe partial comparisons in critical paths.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (2 rules)
  • V-248581 OL 8 must require users to provide a password for privilege escalation. prevents CWE-863
  • V-252656 The OL 8 operating system must not be configured to bypass password requirements for privilege escalation. prevents CWE-863
RHEL 7 (1 rule)
  • V-204430 The Red Hat Enterprise Linux operating system must be configured so that users must re-authenticate for privilege escalation. prevents CWE-863
RHEL 8 (1 rule)
  • V-251712 The RHEL 8 operating system must not be configured to bypass password requirements for privilege escalation. prevents CWE-863

References