Cyber Resilience

CVE-2026-28305

Access Control in Solarwinds Serv-U ≤ 2026.3

Access Control
Published
21 July 2026
Modified
24 July 2026
Patch / advisory
View advisory
CVSS Score v3.1 9.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
EPSS Score 0.0055 43th percentile
Risk Priority 70 floored blend · peak EPSS

Summary

CVE-2026-28305 is a critical-severity Authorization Bypass Through User-Controlled Key (CWE-639) vulnerability in Solarwinds Serv-U. Its CVSS base score is 9.1 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 43th 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 AC-3 (Access Enforcement) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access Control

EU & UK References

Vulnerability Data

SolarWinds Serv-U is affected by an insecure direct object reference (IDOR) vulnerability that can lead to remote code execution as root. A domain account with admin privileges and read and write access to the home directory is required. The impact…

more

is lower in Windows deployments.

CWE(s)
CWE-639

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

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 →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
Why these techniques?

IDOR in public-facing Serv-U server directly enables exploitation for RCE (T1190) and privilege escalation to root (T1068) from an authenticated admin account.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-28317Same product: Solarwinds Serv-U
CVE-2026-28308Same product: Solarwinds Serv-U
CVE-2026-28302Same product: Solarwinds Serv-U
CVE-2025-40541Same product: Solarwinds Serv-U
CVE-2026-28316Same product: Solarwinds Serv-U
CVE-2026-28314Same product: Solarwinds Serv-U
CVE-2026-28313Same product: Solarwinds Serv-U
CVE-2026-28312Same product: Solarwinds Serv-U
CVE-2026-28310Same product: Solarwinds Serv-U
CVE-2026-28306Same product: Solarwinds Serv-U

Affected Assets

solarwinds
serv-u
≤ 2026.3

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • AC-3 Access Enforcement
  • AC-6 Least Privilege
  • AC-4 Information Flow Enforcement
Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)

—

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement good match
prevent

Directly enforces authorization checks on object references so a domain admin cannot access or execute against arbitrary user home directories.

AC-6 Least Privilege partial match
prevent

Limits the scope of the required domain-admin account, reducing the set of objects that can be reached via the IDOR flaw.

AC-4 Information Flow Enforcement partial match
prevent

Enforces information-flow rules that block unauthorized direct references between authenticated sessions and file-system objects.

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 full match
prevents

Enforcing authorization policy and least privilege directly blocks user-controlled key tampering that bypasses access checks.

PR.IR-01 mostly match
prevents

Logical access controls prevent unauthorized data access that results from missing authorization checks on object references.

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
detects

Security testing can detect missing authorization checks but does not prevent the weakness in production.

A.8.3 Information access restriction mostly match
prevents

Information access restriction explicitly enforces that users may only retrieve data they are authorized to see, directly addressing user-controlled key bypass.

A.5.15 Access control partial match
prevents

Access control policy directly requires enforcement of authorization rules that prevent unauthorized access via manipulated keys.

A.5.18 Access rights partial match
prevents

Managing access rights includes ensuring users can only access their own records and not bypass authorization by altering identifiers.

A.8.2 Privileged access rights partial match
mitigates

Privileged access rights control restricts what data each user may access, mitigating direct object reference attacks.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle includes authorization design but does not itself implement runtime access checks.

References