CVE-2026-15996

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.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.16	Product Release Notes
https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.10	Product Release Notes
https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.7	Product Release Notes
https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.3	Product Release Notes

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:github:enterprise_server::::::::
	cpe:2.3:a:github:enterprise_server::::::::
	cpe:2.3:a:github:enterprise_server::::::::
	cpe:2.3:a:github:enterprise_server::::::::

History

No history.

Information

Published : 2026-08-05 21:16

Updated : 2026-08-18 18:08

NVD link : CVE-2026-15996

Mitre link : CVE-2026-15996

CVE.ORG link : CVE-2026-15996

JSON object : View

Products Affected

github

enterprise_server

CWE

CWE-674

Uncontrolled Recursion

{"id": "CVE-2026-15996", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-15996", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-08-06T13:48:48.535295Z"}}], "cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 3.9}], "cvssMetricV40": [{"type": "Secondary", "source": "product-cna@github.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 6.6, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "valueDensity": "NOT_DEFINED", "vectorString": "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", "exploitMaturity": "UNREPORTED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "NONE", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "product-cna@github.com", "affectedData": [{"vendor": "GitHub", "product": "Enterprise Server", "versions": [{"status": "affected", "changes": [{"at": "3.17.16", "status": "unaffected"}], "version": "3.17.0", "versionType": "semver", "lessThanOrEqual": "3.17.15"}, {"status": "affected", "changes": [{"at": "3.18.10", "status": "unaffected"}], "version": "3.18.0", "versionType": "semver", "lessThanOrEqual": "3.18.9"}, {"status": "affected", "changes": [{"at": "3.19.7", "status": "unaffected"}], "version": "3.19.0", "versionType": "semver", "lessThanOrEqual": "3.19.6"}, {"status": "affected", "changes": [{"at": "3.20.3", "status": "unaffected"}], "version": "3.20.0", "versionType": "semver", "lessThanOrEqual": "3.20.2"}], "defaultStatus": "affected"}]}], "published": "2026-08-05T21:16:57.250", "references": [{"url": "https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.16", "tags": ["Product", "Release Notes"], "source": "product-cna@github.com"}, {"url": "https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.10", "tags": ["Product", "Release Notes"], "source": "product-cna@github.com"}, {"url": "https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.7", "tags": ["Product", "Release Notes"], "source": "product-cna@github.com"}, {"url": "https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.3", "tags": ["Product", "Release Notes"], "source": "product-cna@github.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "product-cna@github.com", "description": [{"lang": "en", "value": "CWE-674"}]}], "descriptions": [{"lang": "en", "value": "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."}], "lastModified": "2026-08-18T18:08:11.760", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "42CD4A0C-A4D0-4C5E-B971-11B3AD5F9D1E", "versionEndExcluding": "3.17.16"}, {"criteria": "cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "B3D5BD25-0F18-4915-9399-D42302247396", "versionEndExcluding": "3.18.10", "versionStartIncluding": "3.18.0"}, {"criteria": "cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "4FF939CE-B42A-4091-ACF0-AF80FFBFDC25", "versionEndExcluding": "3.19.7", "versionStartIncluding": "3.19.0"}, {"criteria": "cpe:2.3:a:github:enterprise_server:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "BA3298CD-3841-491D-8056-7AC03FC6473F", "versionEndExcluding": "3.20.3", "versionStartIncluding": "3.20.0"}], "operator": "OR"}]}], "sourceIdentifier": "product-cna@github.com"}