GitHub Enterprise Server up to 3.18.5/3.19.2 cross site scripting

CVSS Meta Temp Score
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CTI Interest Score
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4.4$0-$5k0.00

Summaryinfo

A vulnerability was found in GitHub Enterprise Server up to 3.18.5/3.19.2. It has been rated as problematic. The impacted element is an unknown function. This manipulation causes cross site scripting. This vulnerability appears as CVE-2026-2266. The attack may be initiated remotely. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability has been found in GitHub Enterprise Server up to 3.18.5/3.19.2 and classified as problematic. Affected by this vulnerability is an unknown function. The manipulation with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. The summary by CVE is:

An improper neutralization of input vulnerability was identified in GitHub Enterprise Server that allowed DOM-based cross-site scripting via task list content. The task list content extraction logic did not properly re-encode browser-decoded text nodes before rendering, allowing user-supplied HTML to be injected into the page. An authenticated attacker could craft malicious task list items in issues or pull requests to execute arbitrary scripts in the context of another user's browser session. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.20 and was fixed in versions 3.18.6 and 3.19.3. This vulnerability was reported via the GitHub Bug Bounty program.

The weakness was presented by André Storfjord Kristiansen. It is possible to read the advisory at docs.github.com. This vulnerability is known as CVE-2026-2266 since 02/09/2026. The exploitation appears to be easy. The attack can be launched remotely. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

Upgrading to version 3.18.6 or 3.19.3 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-0682). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

  • Microsoft GitHub Enterprise

Productinfo

Type

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 4.4
VulDB Meta Temp Score: 4.4

VulDB Base Score: 3.5
VulDB Temp Score: 3.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.4
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Enterprise Server 3.18.6/3.19.3

Timelineinfo

02/09/2026 CVE reserved
03/10/2026 +29 days VulDB entry created
03/11/2026 +0 days Advisory disclosed
03/14/2026 +3 days VulDB entry last update

Sourcesinfo

Advisory: docs.github.com
Researcher: André Storfjord Kristiansen
Status: Confirmed

CVE: CVE-2026-2266 (🔒)
GCVE (CVE): GCVE-0-2026-2266
GCVE (VulDB): GCVE-100-350203
CERT Bund: WID-SEC-2026-0682 - Microsoft GitHub Enterprise Server: Mehrere Schwachstellen

Entryinfo

Created: 03/11/2026 00:06
Updated: 03/14/2026 05:24
Changes: 03/11/2026 00:06 (68), 03/12/2026 06:17 (7), 03/14/2026 05:24 (12)
Complete: 🔍
Cache ID: 216:184:103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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