CVE-2021-42857 | Directory Traversal Partial Write at AgentDaServlet

It was discovered that the SteelCentral AppInternals Dynamic Sampling Agent's (DSA) AgentDaServlet has directory traversal vulnerabilities at the "/api/appInternals/1.0/agent/da/pcf" API. The affected endpoint does not have any validation of the user's input that allows a malicious payload to be injected.

Published: 2022-03-10 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-42857 is rated Moderate Risk (43.2/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.46%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-42857

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-09-02 0.56% 0.46% -0.10%
2 2025-03-30 0.49% 0.56% +0.07%
3 2025-03-29 — 0.49% —

Full EPSS history (7 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-42857

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 1.4 [email protected]
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 1.4 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-42857

Affected software / configurations for CVE-2021-42857

Vendor Product Version Raw CPE
riverbed steelcentral_appinternals_dynamic_sampling_agent >= 11.0.0, < 11.8.8 cpe:2.3:a:riverbed:steelcentral_appinternals_dynamic_sampling_agent:*:*:*:*:*:*:*:*
riverbed steelcentral_appinternals_dynamic_sampling_agent >= 12.0.0, < 12.13.0 cpe:2.3:a:riverbed:steelcentral_appinternals_dynamic_sampling_agent:*:*:*:*:*:*:*:*
riverbed steelcentral_appinternals_dynamic_sampling_agent 10.0.0 cpe:2.3:a:riverbed:steelcentral_appinternals_dynamic_sampling_agent:10.0.0:*:*:*:*:*:*:*

References for CVE-2021-42857

cvelogic Threat Intelligence