CVE-2026-21788: HCL Connections is vulnerable to a cross-site scripting attack where an attacker may leverage this issue to ex

Routine

MEDIUM 5.4DOWNGRADE

CVE-2026-21788 is a medium-severity flaw (CVSS 5.4) affecting connections. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

HCL Connections is vulnerable to a cross-site scripting attack where an attacker may leverage this issue to execute arbitrary script code in the browser of an unsuspecting user which leads to executing malicious script code. This may allow the attacker steal cookie-based authentication credentials and comprise user's account then launch other attacks.

Why this priority

No elevated risk signals yet

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.2% (top 94%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-03-19
Last modified	2026-06-17

Publisher (CNA): HCL Software · Vendor: hcltech

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-19 09:16 UTCPublished CVE record published
2026-06-17 10:19 UTCUpdated Record last modified

hcltech connections DOWNGRADE

Affected: 8.0 · 8.0 cumulative_release1 · 8.0 cumulative_release10 · 8.0 cumulative_release11 · 8.0 cumulative_release12 · 8.0 cumulative_release2 · 8.0 cumulative_release3 · 8.0 cumulative_release4

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

1. Check installed version

apt-cache policy connections || rpm -q connections || connections --version

2. No fixed release: DOWNGRADE to a release before 8.0 (Debian / Ubuntu)

apt-cache madison connections sudo apt install connections=<VERSION_BEFORE_8.0> sudo apt-mark hold connections

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list connections sudo dnf downgrade connections-<VERSION_BEFORE_8.0> sudo dnf versionlock add connections

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-21788?

connections: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-21788 being exploited?

CVE-2026-21788 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-21788 affect?

CVE-2026-21788 affects connections. Severity is medium (CVSS 5.4). HCL Connections is vulnerable to a cross-site scripting attack where an attacker may leverage this issue to execute arbitrary script code in the browser of an unsuspecting user which leads to executing malicious script code. This may allow

How urgent is CVE-2026-21788?

Priority 20/100. No elevated risk signals yet.

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References

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