A vulnerability in the interprocess communication (IPC) channel of Cisco AnyConnect Secure Mobility Client Software could allow an authenticated, local attacker to cause a targeted AnyConnect user to execute a malicious script. The vulnerability is due to a lack of authentication to the IPC listener. An attacker could exploit this vulnerability by sending crafted IPC messages to the AnyConnect client IPC listener. A successful exploit could allow an attacker to cause the targeted AnyConnect user to execute a script. This script would execute with the privileges of the targeted AnyConnect user. In order to successfully exploit this vulnerability, there must be an ongoing AnyConnect session by the targeted user at the time of the attack. To exploit this vulnerability, the attacker would also need valid user credentials on the system upon which the AnyConnect client is being run. Cisco has not released software updates that address this vulnerability.
CVE-2020-3556
This high-severity CVE scores 7.3 under NVD CVSS v3. EPSS exploit probability: 0.4% (36th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.
- CVSS v3
- 7.3
- EG Score
- 7.3HIGHmedium confidence
- EG Risk
- 33EG Risk 33/100CISA SSVC
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity73% × 45%Exploitation0% × 40%Automatability0% × 15%CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix. - EPSS PROB
- 0.4%
- EPSS %ILE
- 36th
- KEV
- Not listed
CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).
No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table
Published
November 6, 2020
Last Modified
November 21, 2024
References (2)
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 6× in last 7d / 24× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
Showing the most recent 100 of 151 total refreshes for this CVE.
- 2026-10-05 17:39 UTCEPSS rescore
- 2026-10-04 23:18 UTCEPSS rescore
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- 2026-09-30 15:18 UTCEG score recompute
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- 2026-07-23 01:53 UTCEG score recompute
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- 2026-07-22 14:05 UTCEPSS rescore
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- 2026-07-20 17:04 UTCEPSS rescore
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- 2026-06-25 13:48 UTCEPSS rescore
- 2026-06-24 14:03 UTCEPSS rescore
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Frequently asked(5)
What is CVE-2020-3556?
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What is the CVSS score of CVE-2020-3556?
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Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2020-3556
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