Denial of service vulnerability in GitHub Enterprise Server allowed unauthenticated service disruption via deeply nested request parameters
Summary
| CVE | CVE-2026-15996 |
|---|---|
| State | PUBLISHED |
| Assigner | GitHub_P |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-05 21:16:57 UTC |
| Updated | 2026-08-18 18:08:11 UTC |
| Description | A denial of service vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to cause excessive CPU consumption and exhaust the pool of request-handling worker processes by sending a crafted form-encoded HTTP POST request containing deeply nested parameters. Because request parameters were parsed before routing and authentication, any POST endpoint could be used to trigger the condition, which could render the instance unresponsive. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.3, 3.19.7, 3.18.10, and 3.17.16. |
Risk And Classification
Primary CVSS: v4.0 6.6 MEDIUM from [email protected]
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.004000000 probability, percentile 0.332240000 (date 2026-08-18)
Problem Types: CWE-674 | CWE-674 CWE-674 Uncontrolled Recursion
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 6.6 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/C... |
| 4.0 | CNA | CVSS | 6.6 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U |
| 3.1 | [email protected] | Primary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
LowAttack Requirements
NonePrivileges Required
NoneUser Interaction
NoneConfidentiality
NoneIntegrity
NoneAvailability
HighSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
NoneAvailability
HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Application | Github | Enterprise Server | All | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | GitHub | Enterprise Server | affected 3.17.0 3.17.15 semver | Not specified |
| CNA | GitHub | Enterprise Server | affected 3.18.0 3.18.9 semver | Not specified |
| CNA | GitHub | Enterprise Server | affected 3.19.0 3.19.6 semver | Not specified |
| CNA | GitHub | Enterprise Server | affected 3.20.0 3.20.2 semver | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| docs.github.com/en/[email protected]/admin/release-notes | [email protected] | docs.github.com | Product, Release Notes |
| docs.github.com/en/[email protected]/admin/release-notes | [email protected] | docs.github.com | Product, Release Notes |
| docs.github.com/en/[email protected]/admin/release-notes | [email protected] | docs.github.com | Product, Release Notes |
| docs.github.com/en/[email protected]/admin/release-notes | [email protected] | docs.github.com | Product, Release Notes |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.