CVE-2021-42856Network attack vector

Browser script execution via unchecked Metric parameter

Published Mar 9, 2022 · Updated Sep 17, 2024

Reflected XSS in SteelCentral AppInternals Dynamic Sampling Agent allows remote attackers to execute script via Metric input. The /DsaDataTest endpoint reflects the unchecked Metric parameter into its response without neutralizing attacker-supplied markup. Exploitation requires a victim to open the crafted request and exposes information available to that browser session.

CVSS severity4.7
Medium
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in SteelCentral AppInternals Dynamic Sampling Agent allows remote attackers to execute script via Metric input. The /DsaDataTest endpoint reflects the unchecked Metric parameter into its response without neutralizing attacker-supplied markup. Exploitation requires a victim to open the crafted request and exposes information available to that browser session.

The record

CVE
CVE-2021-42856
Published
Mar 9, 2022
Updated
Sep 17, 2024
Vendor
Riverbed Technology
Product
SteelCentral AppInternals Dynamic Sampling Agent
Classifications
CWE-20, CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 9, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.x
  2. Affected versionversion=11.8.8 <11.8.8
  3. Affected versionversion=12.13.0 <12.13.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Riverbed Technology · SteelCentral AppInternals Dynamic Sampling Agentversion=10.x; version=11.8.8 <11.8.8; version=12.13.0 <12.13.0

Published CVSS scores

6.1NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.3NIST National Vulnerability DatabaseAV:N/AC:M/Au:N/C:N/I:P/A:N
4.7Government Technology Agency of Singapore Cyber Security GroupCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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