CVE-2020-26234

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Opencast before versions 8.9 and 7.9 disables HTTPS hostname verification of its HTTP client used for a large portion of

Opencast before versions 8.9 and 7.9 disables HTTPS hostname verification of its HTTP client used for a large portion of Opencast's HTTP requests. Hostname verification is an important part when using HTTPS to ensure that the presented certificate is valid for the host. Disabling it can allow for man-in-the-middle attacks.

This problem is fixed in Opencast 7.9 and Opencast 8.8 Please be aware that fixing the problem means that Opencast will not simply accept any self-signed certificates any longer without properly importing them. If you need those, please make sure to import them into the Java key store. Better yet, get a valid certificate.

MEDIUM · CVSS 4.8 EPSS 0.00276

EPSS exploitation odds0.28% · top 80%

Monitor

No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence

No Sigma yet — build one → YARA rules0

Look this up elsewhere - one-click external pivots

NVD CVE.org CISA Exploit-DB GitHub PoC VulnCheck KEV GreyNoise

▸ How to read a CVE - triage first, then detect and patch

This page is every public fact about CVE-2020-26234, cross-linked. Its job is to answer one question fast - does this need my attention now? - and then hand you the two things you do about it. Here is how an analyst reads it.

Triage: should I act now? Four signals, and they are not interchangeable:

CVSSseverity - how bad it is IF exploited, 0-10. A high CVSS alone is not urgency; a flaw can be a perfect 10 and never actually be attacked. EPSSprobability - a model’s estimate of the chance it is exploited in the next 30 days, 0-1. This is the “will it actually happen” signal. CISA KEVconfirmed - it is being exploited in the wild right now. The strongest signal on the page; KEV beats any score. Weaponisedavailability - public exploits / PoCs, and especially Metasploit modules rated Excellent / Great. Reliable, packaged exploit code means low-skill attackers can use it today.

How they combine: KEV, or a dependable Metasploit module, means patch now regardless of CVSS. High CVSS + low EPSS + no exploit is real but not an emergency - schedule it. Low CVSS but KEV-listed still gets patched now. The verdict above already weighed these for you; this is how it got there.

Then what - two workflows:

Detectwhen you cannot patch today, follow this CVE to the ATT&CK techniques it enables, then Build a SIEM detection (the green button) - author a rule, test it in Atomic, deploy it. That buys visibility while the patch waits. PatchAffected products / packages tell you if you are exposed; Fixed versions by distribution and Vendor advisories give the exact version that closes it.

Reading order for the panels below: verdict + badges, then Public exploits / Metasploit (is it weaponised), then ATT&CK techniques + Sigma / IDS rules (can I detect it), then Affected products / packages + Fixed versions (am I exposed, what patches it), then Threat actors / IOCs (who uses it), then Scoring & timeline / references (the evidence).

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Severity & exploitation scoring

View on NVD →

CVSS base score

4.8

MEDIUMCVSS v3.1 · [email protected]

EPSS exploitation probability

0.28%

Top 80%odds of exploitation in the next 30 days

CVSS metric silhouette

shape grows toward worst-case

SSVC triage

No SSVC vulnrichment for this CVE. CISA's Vulnrichment program scores newer CVEs (~2024 onwards) plus selected older critical ones. Use the EPSS probability + KEV status to triage instead.

CVSS vector breakdown

Exploitability - how they get in

Attack Vector

Network Adjacent Local Physical

Attack Complexity

Low High

Privileges Required

None Low High

User Interaction

None Required

Scope

Unchanged Changed

Impact - what breaks

Confidentiality

None Low High

Integrity

None Low High

Availability

None Low High

VECTORCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N

Lifecycle

08 Dec 2020Published to NVD
17 Jun 2026Last modified

Every entry is a recorded date - NVD publish/modify, CISA KEV add, public exploit disclosure. No inferred events.

Attack path

Full kill chain

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ATT&CK techniques

Techniques this CVE enables. Pills with a solid outline are high confidence - named directly in ATT&CK or Nuclei, or human-curated by CTID; the rest are inferred from the weakness type using MITRE's CVE Mapping Methodology and the CWE → CAPEC chain. Broad, generic-weakness guesses are filtered out. A small N× marks a technique that N independent sources agree on.

T1190 · Exploit Public-Facing Application

▤ Build a SIEM detection for these techniques