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Review reviewHigh

CVE-2026-8606

GitHub Enterprise Server, enterprise server

A Server-Side Request Forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an attacker to cause the server to issue HTTP requests to internal services via the security advisories package lookup feature. By directing requests to an internal management service and measuring response timing, an attacker could infer the values of sensitive environment variables, including signing secrets and private keys. Exploitation required GitHub Packages to be enabled; on instances not running in private mode the vulnerability was exploitable without authentication, otherwis...

CVSS
7
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.05.27
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7

Vulnerability overview

A Server-Side Request Forgery (SSRF) vulnerability was identified in GitHub Enterprise Server that allowed an attacker to cause the server to issue HTTP requests to internal services via the security advisories package lookup feature. By directing requests to an internal management service and measuring response timing, an attacker could infer the values of sensitive environment variables, including signing secrets and private keys. Exploitation required GitHub Packages to be enabled; on instances not running in private mode the vulnerability was exploitable without authentication, otherwis...

Affected product and versions

Product
GitHub Enterprise Server, enterprise server
Affected versions
>= 3.21.0 < 3.21.1, >= 3.20.0 <= 3.20.2, >= 3.19.0 <= 3.19.6, >= 3.18.0 <= 3.18.9, >= 3.17.0 <= 3.17.15, >= 3.16.0 <= 3.16.18, < 3.16.19, >= 3.17.0 < 3.17.16, >= 3.18.0 < 3.18.10, >= 3.19.0 < 3.19.7, >= 3.20.0 < 3.20.3, 3.21.0
Fixed versions
3.16.19, 3.17.16, 3.18.10, 3.19.7, 3.20.3

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that GitHub Enterprise Server, enterprise server and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/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
CWE
CWE-918