CVE-2026-77987Network attack vector

Remote code execution via notebook viewer SSRF

Published Sep 22, 2026 · Updated Sep 22, 2026

SSRF in the notebook viewer in GitHub Enterprise Server 3.17 through 3.22 allows attackers to extract secrets through response timing. The viewer accepts an explicit port after validating only the URL scheme and host, reaches co-located services, and exposes a timing oracle for secret recovery and subsequent code execution. Network access is required; exploitation is unauthenticated with private mode disabled or available to any authenticated user with private mode enabled.

CVSS severityUnavailable
Unscored
EPSS probability0.88%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SSRF in the notebook viewer in GitHub Enterprise Server 3.17 through 3.22 allows attackers to extract secrets through response timing. The viewer accepts an explicit port after validating only the URL scheme and host, reaches co-located services, and exposes a timing oracle for secret recovery and subsequent code execution. Network access is required; exploitation is unauthenticated with private mode disabled or available to any authenticated user with private mode enabled.

The record

CVE
CVE-2026-77987
Published
Sep 22, 2026
Updated
Sep 22, 2026
Vendor
Git LFS
Product
GitHub Enterprise Server
Classifications
T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 22, 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=3.17.0 <3.17.* changes=[{"at":"3.17.21","status":"unaffected"}]
  2. Affected versionversion=3.18.0 <3.18.* changes=[{"at":"3.18.15","status":"unaffected"}]
  3. Affected versionversion=3.19.0 <3.19.* changes=[{"at":"3.19.12","status":"unaffected"}]
  4. Affected versionversion=3.20.0 <3.20.* changes=[{"at":"3.20.8","status":"unaffected"}]
  5. Affected versionversion=3.21.0 <3.21.* changes=[{"at":"3.21.6","status":"unaffected"}]
  6. Affected versionversion=3.22.0 <3.22.* changes=[{"at":"3.22.1","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Git LFS · GitHub Enterprise Serverversion=3.17.0 <3.17.* changes=[{"at":"3.17.21","status":"unaffected"}]; version=3.18.0 <3.18.* changes=[{"at":"3.18.15","status":"unaffected"}]; version=3.19.0 <3.19.* changes=[{"at":"3.19.12","status":"unaffected"}]; version=3.20.0 <3.20.* changes=[{"at":"3.20.8","status":"unaffected"}]; version=3.21.0 <3.21.* changes=[{"at":"3.21.6","status":"unaffected"}]; version=3.22.0 <3.22.* changes=[{"at":"3.22.1","status":"unaffected"}]

Published CVSS scores

No CVSS assessment is available in this record.

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.

Activity data is delayed. The latest report is Sep 28, 2026.

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

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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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