CVE-2021-27770

MEDIUMNVD 6.88.8▲
EchelonGraph scoreMEDIUM confidence

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2022-05-13. NVD baseline CVSS 6.8; sources differ by 2.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
6.8
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 1%CVSS: 6.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

The vulnerability was discovered within the “FaviconService”. The service takes a base64-encoded URL which is then requested by the webserver. We assume this service is used by the “meetings”-function where users can specify an external URL where the online meeting will take place.

CVSS v3
6.8
EG Score
8.8(medium)
EPSS
48.8%
KEV
Not listed

Published

May 12, 2022

Last Modified

November 21, 2024

References (2)

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 47× 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.

  1. 2026-07-22 14:06 UTCEPSS rescore
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  70. 2026-05-26 07:17 UTCEPSS rescore
  71. 2026-05-25 22:11 UTCEG score recompute
  72. 2026-05-25 22:11 UTCGHSA enrichment
  73. 2026-05-25 04:37 UTCOSV refresh

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-27770?
CVE-2021-27770 is a medium vulnerability published on May 12, 2022. The vulnerability was discovered within the “FaviconService”. The service takes a base64-encoded URL which is then requested by the webserver. We assume this service is used by the “meetings”-function where users can specify an external URL where the online meeting will take place.
When was CVE-2021-27770 disclosed?
CVE-2021-27770 was first published in the National Vulnerability Database on May 12, 2022, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-27770 actively exploited?
CVE-2021-27770 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 48.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-27770?
CVE-2021-27770 has a CVSS v3 base score of 6.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.8.
How do I remediate CVE-2021-27770?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-27770, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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