Cyber Resilience

CVE-2026-101891

Published
28 September 2026
Modified
28 September 2026
CVSS Score v4 9.3
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:H/VA:H/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 0.0027 18th percentile
Risk Priority 44 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-2026-101891 is a critical-severity Improper Access Control (CWE-284) vulnerability in Watchguard (inferred from references). Its CVSS base score is 9.3 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Boot or Logon Initialization Scripts (T1037); ranked at the 18th 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-2 (Account Management) and AC-3 (Access Enforcement) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

An improper access control vulnerability in an internal API service on WatchGuard Access Points allows an unauthenticated attacker with network access to the AP to obtain a valid API session.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1037 Boot or Logon Initialization Scripts Persistence
Adversaries may use scripts automatically executed at boot or logon initialization to establish persistence.
T1080 Taint Shared Content Lateral Movement
T1090.004 Domain Fronting Command And Control
Adversaries may take advantage of routing schemes in Content Delivery Networks (CDNs) and other services which host multiple domains to obfuscate the intended destination of HTTPS traffic or traffic tunneled through HTTPS.
T1543 Create or Modify System Process Persistence
Adversaries may create or modify system-level processes to repeatedly execute malicious payloads as part of persistence.
T1543.001 Launch Agent Persistence
Adversaries may create or modify launch agents to repeatedly execute malicious payloads as part of persistence.
T1543.003 Windows Service Persistence
Adversaries may create or modify Windows services to repeatedly execute malicious payloads as part of persistence.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-48999Shared CWE-284, CWE-923
CVE-2025-46566Shared CWE-284, CWE-923
CVE-2026-35243Shared CWE-284
CVE-2025-20153Shared CWE-284
CVE-2025-25621Shared CWE-284
CVE-2025-44619Shared CWE-284
CVE-2026-28833Shared CWE-284
CVE-2025-30714Shared CWE-284
CVE-2026-41243Shared CWE-284
CVE-2024-47481Shared CWE-284

Affected Assets

Watchguard
—
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)
  • 13 hardening rules · 4 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V8.4.1
  • V10.3.5
  • V10.5.5
  • V12.3.5

Mitigating Controls (NIST 800-53 r5) AI

Defines account types, assigns/removes access, and reviews accounts to ensure only authorized actors can reach resources.

Directly enforces approved authorizations for logical access, stopping unauthorized actors from reaching resources.

Enforces flow-control policies that restrict information movement between subjects and objects.

Documents duties and assigns access so that no single account can bypass intended restrictions.

Limits each account to the minimum privileges needed, reducing the chance of unauthorized access.

Requires unique identification and authentication of devices before establishing a communications session.

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

PR.AA-05 directly enforces policy-based access management and least privilege, eliminating most improper-access-control defects, yet CWE-284 also covers implementation flaws and design gaps outside a single management control.

PR.PS-01 mostly match
prevents

Hardened baselines and deviation monitoring directly eliminate most configuration-induced access-control defects, yet CWE-284 also encompasses code-level and design flaws outside the scope of configuration management alone.

PR.PS-06 mostly match
prevents

Secure SDLC practices catch most access-control defects during design/coding/testing (mostly), yet leave residual risk from runtime configuration, architecture, and operational controls (partial).

ID.AM-03 partial match
prevents

Documenting authorized flows helps define intended endpoints but does not enforce channel restrictions at runtime.

PR.AA-01 partial match
prevents

PR.AA-01 supplies managed identities/credentials that support but do not implement access-control decisions, so it only partially prevents CWE-284 in either direction.

PR.AA-03 partial match
prevents

Authentication directly blocks unauthenticated actors (partial prevention of CWE-284) but leaves authorization logic, policy enforcement, and role checks untouched, so the control neither eliminates nor fully mitigates the broader weakness.

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.

prevents

A.5.1 only requires that an information security policy and topic-specific policies (including on access control) exist and are reviewed; it does not itself enforce, implement or act on any access restriction, so the weakness can still be exploited (per the owner's explicit rule that governance/dependency clauses score none on effect verbs).

prevents

A.5.15 directly mandates determining requirements, defining/implementing topic-specific access control policy+rules (with explicit references to 8.3, 5.16, 5.18), and enforcing authorized access while preventing unauthorized access, which squarely stops exploitation of most CWE-284 instances; the bounded remainder is the physical slice (explicitly delegated to 7.2-7.4) plus any second-order defects like path traversal that are not authorization decisions.

prevents

A.5.16's identity lifecycle (unique binding, timely disable/remove, no duplicates, oversight of shared/non-human) directly stops most improper access by ensuring the actor in an access decision is correctly identified and authorized; the bounded remainder is non-identity mechanisms in CWE-284 such as path traversal or CSRF that do not turn on actor identity at all.

prevents

A.5.18 directly governs the provisioning, review, adjustment and timely revocation of both physical and logical access rights per business rules, segregation of duties and risk-evaluated changes/terminations; this stops most unauthorized-actor exploitation paths named by CWE-284, with a bounded remainder (e.g. path-traversal or CSRF cases that are not authorization decisions at all)

prevents

A.5.2 defines and assigns roles/responsibilities for protection of information and risk acceptance; it does not itself enforce any access decision and cannot stop exploitation of improper access control (per the owner's labeling rule: governance/dependency clauses do not score on prevent/mitigate verbs)

finds

Ongoing audits and performance reviews of suppliers detect and correct situations where access controls or privilege assignments are weaker than contractually required, limiting an attacker's ability to exploit improper access control in the supplier's environment.

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` (higher-evidence rows only; rows rated `none` are excluded).

Oracle Linux 8 (4 rules)
  • V-248827 OL 8 must not have the rsh-server package installed. prevents CWE-923
  • V-248597 There must be no "shosts.equiv" files on the OL 8 operating system. prevents CWE-284
  • V-248598 There must be no ".shosts" files on the OL 8 operating system. prevents CWE-284
Oracle Linux 9 (2 rules)
  • V-271758 OL 9 file systems must not contain .shosts files. prevents CWE-284
  • V-271757 OL 9 file systems must not contain shosts.equiv files. prevents CWE-284
RHEL 7 (3 rules)
  • V-204442 The Red Hat Enterprise Linux operating system must not have the rsh-server package installed. prevents CWE-923
  • V-204606 The Red Hat Enterprise Linux operating system must not contain .shosts files. prevents CWE-284
  • V-204607 The Red Hat Enterprise Linux operating system must not contain shosts.equiv files. prevents CWE-284
RHEL 8 (4 rules)
  • V-230492 RHEL 8 must not have the rsh-server package installed. prevents CWE-923
  • V-230283 There must be no shosts.equiv files on the RHEL 8 operating system. prevents CWE-284
  • V-230284 There must be no .shosts files on the RHEL 8 operating system. prevents CWE-284

References