CVE-2019-1721

MEDIUMNVD 6.56.5
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

Score 6.5 from GitHub Security Advisory published 2022-05-13. NVD baseline CVSS 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
6.5EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 2.0%CVSS: 6.5Exploit: None knownExposed services: Not assessed

No fix has been recorded since the CVE record was published in 2019 — use a compensating control (WAF / firewall / segmentation) and check the vendor's advisory.

The CVE record's CNA (Cisco Systems, Inc.) lists Cisco TelePresence Video Communication Server (VCS) versions before X12.5.1 as affected. No release containing a fix is confirmed on record.

A vulnerability in the phone book feature of Cisco Expressway Series and Cisco TelePresence Video Communication Server (VCS) could allow an authenticated, remote attacker to cause the CPU to increase to 100% utilization, causing a denial of service (DoS) condition on an affected system. The vulnerability is due to improper handling of the XML input. An attacker could exploit this vulnerability by sending a Session Initiation Protocol (SIP) message with a crafted XML payload to an affected device. A successful exploit could allow the attacker to exhaust CPU resources, resulting in a DoS condition. Manual intervention may be required to recover the device. This vulnerability is fixed in Cisco Expressway Series and Cisco TelePresence Video Communication Server Releases X12.5.1 and later.

CVSS v3
6.5
EG Score
6.5MEDIUMmedium confidence
EG Risk
30
EG Risk 30/100

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 computed (value × EchelonGraph’s weight)
Severity65% × 45%
The EG Score, 6.5 of 10.
Exploitation2.0% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: No fix has been recorded since the CVE record was published in 2019. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and check the vendor's advisory for a fix.
EPSS PROB
2.0%
EPSS %ILE
80th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

No fix has been recorded since the CVE record was published in 2019. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and check the vendor's advisory for a fix.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

April 18, 2019

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 9× in last 7d / 26× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 88 of 149 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 12 repeat rows among the latest 100 are merged into the row they repeat. The 61 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-14 16:28 UTCEPSS rescoreEPSS 2.0% · 80th percentile
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Frequently asked(5)

What is CVE-2019-1721?
CVE-2019-1721 is a medium-severity vulnerability; its CVE record was published on April 18, 2019. A vulnerability in the phone book feature of Cisco Expressway Series and Cisco TelePresence Video Communication Server (VCS) could allow an authenticated, remote attacker to cause the CPU to increase to 100% utilization, causing a denial of service (DoS) condition on an affected system. The…
When was CVE-2019-1721 made public?
CVE-2019-1721 was made public on April 17, 2019: that is the date its CVE record's CNA, Cisco Systems, Inc., gives for when the vulnerability was made public. The CVE record itself was published on April 18, 2019. EchelonGraph's copy of the record carries a last-modified date of November 21, 2024; the record at its source may have been updated since.
Is CVE-2019-1721 actively exploited?
CVE-2019-1721 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2.0% probability of exploitation in the next 30 days (80th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2019-1721?
CVE-2019-1721 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2019-1721?
No fix for CVE-2019-1721 has been recorded since its CVE record was published in 2019. Restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and check the vendor's advisory for a fix. The CVE record's CNA (Cisco Systems, Inc.) lists Cisco TelePresence Video Communication Server (VCS) versions before X12.5.1 as affected. No release containing a fix is confirmed on record.

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