CVE-2021-1517 | Cisco Webex Meetings and Webex Meetings Server Multimedia Sharing Security Bypass Vulnerability

A vulnerability in the multimedia viewer feature of Cisco Webex Meetings and Cisco Webex Meetings Server could allow an authenticated, remote attacker to bypass security protections. This vulnerability is due to unsafe handling of shared content within the multimedia viewer feature. An attacker could exploit this vulnerability by sharing a file through the multimedia viewer feature. A successful exploit could allow the attacker to bypass security protections and prevent warning dialogs from appearing before files are offered to other users.

Published: 2021-06-04 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-1517 is rated Low Risk (39/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.83%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

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-2021-1517

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 2026-06-15 0.18% 0.83% +0.65%
2 2025-03-30 0.28% 0.18% -0.11%
3 2025-03-29 — 0.28% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-1517

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.0 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/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:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
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.
 3.1 1.4 [email protected]
4.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/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:L)
A normal user session is enough; they don’t have to be admin.
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.
 2.8 1.4 [email protected]
4.0 2.0 MEDIUM
AV:N/AC:L/Au:S/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:S)
A single authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.0 2.9 [email protected]

Weakness enumeration for CVE-2021-1517

Affected software / configurations for CVE-2021-1517

Vendor Product Version Raw CPE
cisco webex_meetings_online 41.3.5 cpe:2.3:a:cisco:webex_meetings_online:41.3.5:*:*:*:*:*:*:*
cisco webex_meetings_server < 3.0 cpe:2.3:a:cisco:webex_meetings_server:*:*:*:*:*:*:*:*
cisco webex_meetings_server 3.0 cpe:2.3:a:cisco:webex_meetings_server:3.0:-:*:*:*:*:*:*
cisco webex_meetings_server 3.0 cpe:2.3:a:cisco:webex_meetings_server:3.0:maintenance_release1:*:*:*:*:*:*
cisco webex_meetings_server 3.0 cpe:2.3:a:cisco:webex_meetings_server:3.0:maintenance_release2:*:*:*:*:*:*
cisco webex_meetings_server 3.0 cpe:2.3:a:cisco:webex_meetings_server:3.0:maintenance_release3:*:*:*:*:*:*
cisco webex_meetings_server 4.0 cpe:2.3:a:cisco:webex_meetings_server:4.0:-:*:*:*:*:*:*
cisco webex_meetings_server 4.0 cpe:2.3:a:cisco:webex_meetings_server:4.0:maintenance_release1:*:*:*:*:*:*
cisco webex_meetings_server 4.0 cpe:2.3:a:cisco:webex_meetings_server:4.0:maintenance_release2:*:*:*:*:*:*
cisco webex_meetings_server 4.0 cpe:2.3:a:cisco:webex_meetings_server:4.0:maintenance_release3:*:*:*:*:*:*
cisco webex_meetings_server 4.0 cpe:2.3:a:cisco:webex_meetings_server:4.0:maintenance_release3_security_patch3:*:*:*:*:*:*
cisco webex_meetings_server 4.0 cpe:2.3:a:cisco:webex_meetings_server:4.0:maintenance_release3_security_patch4:*:*:*:*:*:*

References for CVE-2021-1517

cvelogic Threat Intelligence