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PatchSiren cyber security CVE debrief

CVE-2026-21789 HCLSoftware CVE debrief

A broken access control vulnerability in HCL Connections may allow unauthorized users to update data under certain conditions. The vulnerability is classified as CWE-863 (Incorrect Authorization) and carries a CVSS 3.1 score of 4.6 (Medium severity). The attack vector is network-based with low attack complexity, requiring low privileges and user interaction. The vulnerability was published to the NVD on 2026-05-18 with a status of 'Deferred'. HCL Software has published a knowledge base article with additional details. No known exploitation in ransomware campaigns has been reported, and the vulnerability is not listed in CISA's Known Exploited Vulnerabilities catalog.

Vendor
HCLSoftware
Product
Connections
CVSS
MEDIUM 4.6
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-18
Original CVE updated
2026-05-18
Advisory published
2026-05-18
Advisory updated
2026-05-18

Who should care

Organizations running HCL Connections for enterprise collaboration; security teams responsible for access control validation; compliance officers monitoring data integrity controls; administrators managing user privilege boundaries in collaboration platforms

Technical summary

The vulnerability stems from incorrect authorization controls (CWE-863) in HCL Connections, a collaboration platform. The CVSS 3.1 vector (AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N) indicates an attacker with low privileges can exploit this over the network with low complexity, though user interaction is required. Successful exploitation could result in low-impact confidentiality and integrity violations, with no availability impact. The 'Deferred' status in NVD suggests the entry may be awaiting additional analysis or vendor coordination.

Defensive priority

medium

Recommended defensive actions

  • Review HCL Software security advisory for affected product versions and patch availability
  • Assess HCL Connections deployments for exposure to unauthorized data modification
  • Implement principle of least privilege for user accounts accessing Connections
  • Monitor access logs for anomalous data update activities in HCL Connections
  • Apply vendor-provided security patches when available
  • Consider additional access controls or network segmentation for sensitive Connections deployments

Evidence notes

CVE description indicates broken access control allowing unauthorized data updates. CVSS vector confirms network attack vector with low complexity, low privileges required, and user interaction needed. NVD status is 'Deferred'. Vendor attribution to HCL Software based on reference domain and PSIRT contact email.

Official resources

2026-05-18