CVE-2020-12443

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 3.6%, top 12% of all CVEs by exploit prediction. 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).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 4%CVSS: 9.8Exploit: None knownExposed: 0

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

BigBlueButton before 2.2.6 allows remote attackers to read arbitrary files because the presfilename (lowercase) value can be a .pdf filename while the presFilename (mixed case) value has a ../ sequence. This can be leveraged for privilege escalation via a directory traversal to bigbluebutton.properties. NOTE: this issue exists because of an ineffective mitigation to CVE-2020-12112 in which there was an attempted fix within an NGINX configuration file, without considering that the relevant part of NGINX is case-insensitive.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
50(Track)
EG Risk 50/100SSVC: Track

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
Severity98% × 45%
Exploitation4% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
4%
EPSS %ILE
89%
KEV
Not listed

Published

April 29, 2020

Last Modified

November 21, 2024

Advisory Details (2)

Auto-updated Sep 20, 2026
🔬 Proof of concept available. Upstream fix merged — awaiting tagged release. Sources: github_pr.
generic🟡 PoC Available

GitHub - mclab-hbrs/BBB-POC: Proof Of Concept Exploits For BBB · GitHub

https://github.com/mclab-hbrs/BBB-POC
github_pr

Return 404 error when presentation file download is not allowed.

Fix merged in bigbluebutton/bigbluebutton PR #9259 on 2020-04-25 — awaiting tagged release

https://github.com/bigbluebutton/bigbluebutton/pull/9259/commits/b21ca8355a57286a1e6df96984b3a4c57679a463

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 6× in last 7d / 26× 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.

  1. 2026-09-24 13:59 UTCEPSS rescore
  2. 2026-09-22 14:43 UTCEPSS rescore
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  1. 2026-08-26 14:42 UTCEPSS rescore
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  31. 2026-07-23 01:48 UTCEG score recompute
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  73. 2026-06-23 21:31 UTCEPSS rescore
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  75. 2026-06-22 14:23 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2020-12443?
CVE-2020-12443 is a critical vulnerability published on April 29, 2020. BigBlueButton before 2.2.6 allows remote attackers to read arbitrary files because the presfilename (lowercase) value can be a .pdf filename while the presFilename (mixed case) value has a ../ sequence. This can be leveraged for privilege escalation via a directory traversal to…
When was CVE-2020-12443 disclosed?
CVE-2020-12443 was first published in the National Vulnerability Database on April 29, 2020, 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-2020-12443 actively exploited?
CVE-2020-12443 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 4% probability of exploitation in the next 30 days, which ranks it in the top 10.8% of all scored CVEs.
What is the CVSS score of CVE-2020-12443?
CVE-2020-12443 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2020-12443?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-12443, 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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