CVE-2021-42856: It was discovered that the /DsaDataTest endpoint is susceptible to Cross-site scripting (XSS) attack

Routine

MEDIUM 4.7UPGRADE

CVE-2021-42856 is a medium-severity flaw (CVSS 4.7) affecting steelcentral appinternals dynamic sampling agent. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

It was discovered that the /DsaDataTest endpoint is susceptible to Cross-site scripting (XSS) attack. It was noted that the Metric parameter does not have any input checks on the user input that allows an attacker to craft its own malicious payload to trigger a XSS vulnerability.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	4.7 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.6% (top 51%)
CISA exploited list	No
Weakness	CWE-20, CWE-79
Published	2022-03-10
Last modified	2026-06-17

Publisher (CNA): Government Technology Agency of Singapore Cyber Security Group (GovTech CSG) · Vendor: riverbed

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

Am I affected?

Timeline

2022-03-10 17:44 UTCPublished CVE record published
2026-06-17 04:10 UTCUpdated Record last modified

riverbed steelcentral appinternals dynamic sampling agent UPGRADE

Affected: >= 11.0.0 and < 11.8.8 · >= 12.0.0 and < 12.13.0 · 10.0.0

Fixed in: 11.8.8, 12.13.0

Safe to downgrade to: a release before 10.0.0

1. Check installed version

apt-cache policy steelcentral-appinternals-dynamic-sampling-agent || rpm -q steelcentral-appinternals-dynamic-sampling-agent || steelcentral-appinternals-dynamic-sampling-agent --version

2. UPGRADE to 11.8.8 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade steelcentral-appinternals-dynamic-sampling-agent

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade steelcentral-appinternals-dynamic-sampling-agent

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 10.0.0 (Debian / Ubuntu)

apt-cache madison steelcentral-appinternals-dynamic-sampling-agent sudo apt install steelcentral-appinternals-dynamic-sampling-agent=<VERSION_BEFORE_10.0.0> sudo apt-mark hold steelcentral-appinternals-dynamic-sampling-agent

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list steelcentral-appinternals-dynamic-sampling-agent sudo dnf downgrade steelcentral-appinternals-dynamic-sampling-agent-<VERSION_BEFORE_10.0.0> sudo dnf versionlock add steelcentral-appinternals-dynamic-sampling-agent

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-2021-42856?

steelcentral appinternals dynamic sampling agent: upgrade to 11.8.8, 12.13.0. Exact commands for each OS are on this page.

Is CVE-2021-42856 being exploited?

CVE-2021-42856 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-2021-42856 affect?

CVE-2021-42856 affects steelcentral appinternals dynamic sampling agent. Severity is medium (CVSS 4.7). It was discovered that the /DsaDataTest endpoint is susceptible to Cross-site scripting (XSS) attack. It was noted that the Metric parameter does not have any input checks on the user input that allows an attacker to craft its own malicious

How urgent is CVE-2021-42856?

Priority 29/100. No elevated risk signals yet.

Related CVEs

CVE-2021-42857 MEDIUM 5.3 UPGRADE It was discovered that the SteelCentral AppInternals Dynamic Sampling Agent's (DSA) AgentDaServlet has directo
CVE-2021-42855 HIGH 7.8 UPGRADE It was discovered that the SteelCentral AppInternals Dynamic Sampling Agent (DSA) uses the ".debug_command.con
CVE-2021-42854 CRITICAL 9.8 UPGRADE It was discovered that the SteelCentral AppInternals Dynamic Sampling Agent's (DSA) PluginServlet has director
CVE-2021-42853 CRITICAL 9.1 UPGRADE It was discovered that the SteelCentral AppInternals Dynamic Sampling Agent's (DSA) AgentDiagnosticServlet has
CVE-2021-42787 CRITICAL 9.4 UPGRADE It was discovered that the SteelCentral AppInternals Dynamic Sampling Agent's (DSA) AgentConfigurationServlet

References

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