Security Resilience

CVE-2019-11634

Citrix Receiver 4.9

CISA KEVActive ExploitationEUVD ExploitedRansomware-linked
Published
22 May 2019
Modified
12 August 2026
KEV Added
03 November 2021
Patch / advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.081 95th percentile
Risk Priority 97 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-2019-11634 is a critical-severity Improper Access Control (CWE-284) vulnerability in Citrix Receiver. Its CVSS base score is 9.8 (Critical).

Operationally, ranked in the top 5% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

Deeper analysis AI-assisted summary

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

Citrix Workspace App before version 1904 for Windows contains an incorrect access control vulnerability, tracked as CVE-2019-11634 and assigned CWE-284. The flaw received a CVSS 3.1 base score of 9.8, reflecting network-accessible attack vectors that require no authentication or user interaction and result in high impact to confidentiality, integrity, and availability.

An unauthenticated remote attacker can exploit the weakness to bypass intended access restrictions, potentially obtaining unauthorized control over the affected application and the underlying Windows system. Because the vulnerability is reachable without credentials or user assistance, it can be leveraged directly from the network to read, modify, or disrupt sensitive data and operations.

Citrix has published remediation guidance in security bulletin CTX251986, directing customers to upgrade to Workspace App 1904 or later. The issue also appears in the CISA Known Exploited Vulnerabilities catalog, confirming observed in-the-wild exploitation and underscoring the need for prompt patching.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

Citrix Workspace App before 1904 for Windows has Incorrect Access Control.

CWE(s)
KEV Date Added
03 November 2021

Related Threats

CVEs Like This One

CVE-2023-24486Same product: Citrix Workspace
CVE-2021-22941Same vendor: Citrixboth on KEV
CVE-2023-24489Same vendor: Citrixboth on KEV
CVE-2023-24484Same product: Citrix Workspace
CVE-2023-24485Same product: Citrix Workspace
CVE-2020-8196Same vendor: Citrixboth on KEV
CVE-2020-8193Same vendor: Citrixboth on KEV
CVE-2023-24490Same vendor: Citrix
CVE-2025-24989Shared CWE-284both on KEV
CVE-2012-4681Shared CWE-284both on KEV

Affected Assets

citrix
receiver
4.9
citrix
workspace
≤ 1904

Mitigating Controls

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.

addresses: CWE-284

The access control policy and procedures directly mandate and enforce proper access control mechanisms across the organization.

addresses: CWE-284

Device lock enforces restricted access until re-authentication, directly reducing unauthorized use of active sessions.

addresses: CWE-284

Supervision and review of access control activities directly detects and remediates improper access configurations or usages.

addresses: CWE-284

Explicitly identifying and documenting actions permitted without identification or authentication enforces proper access control boundaries by defining justified exceptions.

addresses: CWE-284

By automatically labeling outputs with security attributes, the control supports attribute-based enforcement and reduces exploitability of improper access control weaknesses.

addresses: CWE-284

Associating and retaining security attributes with data directly supports enforcement of access control decisions across storage, processing, and transmission.

addresses: CWE-284

Requiring prior authorization for each remote access type prevents improper access control over remote connections.

addresses: CWE-284

Requiring authorization of wireless access before allowing connections enforces proper access control for this access method.

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.

blocks

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).

blocks

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.

blocks

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.

blocks

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)

blocks

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

DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.

  • No fine-grained STIG row for CWE-284, a pillar-level weakness. Rules are authored against its narrower children: CWE-749, CWE-1220.

References