CVE-2026-15996

Denial of service vulnerability in GitHub Enterprise Server allowed unauthenticated service disruption via deeply nested request parameters

HIGH
7.5
CVSS Score
Published: August 5, 2026 at 08:12 PM UTC
Updated: October 23, 2026 at 09:10 PM UTC
1 product affected across 1 vendorGitHub Enterprise Server

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Severity
HIGH7.5
Exploit prediction
EPSS 0.8%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 3.17.163.18.0 ≤ v < 3.18.103.19.0 ≤ v < 3.19.73.20.0 ≤ v < 3.20.33.17.03.18.03.19.03.20.0
Affected range stops below 3.17.16, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.18.10, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.19.7, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.20.3, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-674

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