CVE-2026-8034Network attack vector

Internal-service access via URL parser confusion

Published May 7, 2026 · Updated May 7, 2026

Server-side request forgery in GitHub Enterprise Server allows remote attackers to access internal services through the notebook viewer. The hostname validator and HTTP request library parse a crafted URL differently, so a validated hostname can become an unintended request target. Exploitation requires network access to an instance with private mode disabled; the bounded impact is server-side access to internal services.

CVSS severity9.8
Critical
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Server-side request forgery in GitHub Enterprise Server allows remote attackers to access internal services through the notebook viewer. The hostname validator and HTTP request library parse a crafted URL differently, so a validated hostname can become an unintended request target. Exploitation requires network access to an instance with private mode disabled; the bounded impact is server-side access to internal services.

The record

CVE
CVE-2026-8034
Published
May 7, 2026
Updated
May 7, 2026
Vendor
Twitter
Product
GitHub Enterprise Server
Classifications
CWE-918, CWE-436, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 7, 2026CVE publishedPublication date reported by the CVE source.
  2. May 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.16.0 <=3.16.17 changes=[{"at":"3.16.18","status":"unaffected"}]
  2. Affected versionversion=3.17.0 <=3.17.14 changes=[{"at":"3.17.15","status":"unaffected"}]
  3. Affected versionversion=3.18.0 <=3.18.8 changes=[{"at":"3.18.9","status":"unaffected"}]
  4. Affected versionversion=3.19.0 <=3.19.5 changes=[{"at":"3.19.6","status":"unaffected"}]
  5. Affected versionversion=3.20.0 <=3.20.1 changes=[{"at":"3.20.2","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Twitter · GitHub Enterprise Serverversion=3.16.0 <=3.16.17 changes=[{"at":"3.16.18","status":"unaffected"}]; version=3.17.0 <=3.17.14 changes=[{"at":"3.17.15","status":"unaffected"}]; version=3.18.0 <=3.18.8 changes=[{"at":"3.18.9","status":"unaffected"}]; version=3.19.0 <=3.19.5 changes=[{"at":"3.19.6","status":"unaffected"}]; version=3.20.0 <=3.20.1 changes=[{"at":"3.20.2","status":"unaffected"}]

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.9GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
CWE-436Interpretation Conflict
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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