CVE-2026-4821 Details
An improper neutralization of special elements vulnerability was identified in GitHub Enterprise Server that allowed an authenticated Management Console administrator to execute arbitrary OS commands via shell metacharacter injection in proxy configuration fields such as http_proxy. Exploitation of this vulnerability required access to the GitHub Enterprise Server instance and administrator privileges to the Management Console. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, 3.14.26. This vulnerability was reported via the GitHub Bug Bounty program.
View at NVD
Exploit prediction scoring system (EPSS) score for CVE-2026-4821
EPSS (Exploit Prediction Scoring System): EPSS predicts the likelihood that a vulnerability will be exploited in the wild. A higher percentage means a greater chance of an exploit occurring. The EPSS model produces a probability score between 0 and 1 (0 and 100%).
0.01 Probability of exploitation activity being observed over the next 30 days (3nd percentile)
CVSS score for CVE-2026-4821
CVSS (Common Vulnerability Scoring System): An open framework owned and managed by FIRST.Org, Inc. that assigns a numerical score from 0 to 10 to software vulnerabilities to indicate their severity.
7.2 High
Products affected by CVE-2026-4821
Enterprise Server 3.18.0
Enterprise Server 3.18.1
Enterprise Server 3.18.7
Enterprise Server 3.19.0
Enterprise Server 3.19.3
DVE Score by Bitsight AI
DVE scores complement traditional static scoring systems like CVSS with Bitsight AI powered real-time threat intelligence and underground cyber criminal activity so that security teams can reduce alert fatigue and focus on vulnerabilities most likely to be exploited.
Low
More on DVE scores

CVE-2026-4821 Global Footprint

Top 10 Identified Countries

Country Observations Percentage
US 154 60.39%
JP 13 5.10%
AU 12 4.71%
GB 11 4.31%
IE 10 3.92%
CA 9 3.53%
FR 9 3.53%
DE 6 2.35%
SE 5 1.96%
IN 5 1.96%

Is CVE-2026-4821 part of your extended attack surface? Bitsight helps security leaders rapidly identify exposure and detect threats in order to prioritize, communicate, and mitigate risk.

View interactive product tours

CVE-2026-4821 Industry Footprint

Top 10 Identified Industries

*Service provider organizations (typically Technology and Telecommunications) are disproportionally represented in the results given their upstream ownership of end-user infrastructure. See our FAQs.

Industry* Observations Percentage
Technology 228 91.20%
Education 11 4.40%
Telecommunications 4 1.60%
Aerospace/Defense 2 0.80%
Government/Politics 2 0.80%
Manufacturing 2 0.80%
Transportation 1 0.40%

Bitsight Data Discovery and Continuous Threat Scanning

Bitsight, the leading provider in Cyber Risk Management, introduced the next-generation internet scanner Bitsight Groma in May 2024. This technology continuously scans the entire internet to discover assets, collect asset attribution evidence, and identify an ever-growing set of security observations, such as vulnerabilities and misconfigurations. Groma’s scanning activities presently encompass:


  • 40 million-plus monitored organizations
  • 250 million-plus host names
  • 4 billion-plus routable IPv4 and IPv6 addresses

Greynoise’s recent study testifies the speed of Bitsight Groma.

Learn more about Bitsight Groma
Bitsight data discovery
Governance charcoal background

How we use Bitsight Groma data 

Empower Security Research

Bitsight TRACE team investigates security incidents and identifies vulnerabilities and threats.

View latest security research 

See Your External Attack Surface

See what you’re up against across the expanding attack surface. Prioritize what matters most. And mitigate where you’re most vulnerable.

External Attack Surface Management