CVE-2026-1999 Details
An incorrect authorization vulnerability was identified in GitHub Enterprise Server that allowed an attacker to merge their own pull request into a repository without having push access by exploiting an authorization bypass in the enable_auto_merge mutation for pull requests. This issue only affected repositories that allow forking as the attack relies on opening a pull request from an attacker-controlled fork into the target repository. Exploitation was only possible in specific scenarios. It required a clean pull request status and only applied to branches without branch protection rules enabled. This vulnerability affected GitHub Enterprise Server versions prior to 3.19.2, 3.18.5, and 3.17.11, and was fixed in versions 3.19.2, 3.18.5, and 3.17.11. This vulnerability was reported via the GitHub Bug Bounty program.
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Exploit prediction scoring system (EPSS) score for CVE-2026-1999
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%).
0.04 Probability of exploitation activity being observed over the next 30 days (11th percentile)
CVSS score for CVE-2026-1999
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.
6.5 Medium
Products affected by CVE-2026-1999
Enterprise Server 3.16.2
Enterprise Server 3.16.3
Enterprise Server 3.16.4
Enterprise Server 3.17.3
Enterprise Server 3.17.7
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
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CVE-2026-1999 Global Footprint

Top 10 Identified Countries

Country Observations Percentage
US 113 60.43%
CA 10 5.35%
JP 7 3.74%
DE 6 3.21%
SE 6 3.21%
FR 6 3.21%
GB 6 3.21%
IE 6 3.21%
AU 5 2.67%
SG 4 2.14%

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CVE-2026-1999 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 165 89.67%
Education 10 5.43%
Telecommunications 3 1.63%
Aerospace/Defense 2 1.09%
Manufacturing 2 1.09%
Government/Politics 2 1.09%

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