CVE-2026-2266Network attack vector

Authenticated script execution via task-list HTML injection

Published Mar 10, 2026 · Updated Mar 10, 2026

DOM XSS in GitHub Enterprise Server 3.18.0 through 3.18.5 and 3.19.0 through 3.19.2 allows remote authenticated users to run browser scripts. Task-list extraction fails to re-encode browser-decoded text nodes before rendering, so crafted item content becomes executable HTML. Exploitation requires an authenticated attacker to place a malicious task item in an issue or pull request and another user to render it; the injected script then runs in that user’s browser session.

CVSS severity7.4
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

DOM XSS in GitHub Enterprise Server 3.18.0 through 3.18.5 and 3.19.0 through 3.19.2 allows remote authenticated users to run browser scripts. Task-list extraction fails to re-encode browser-decoded text nodes before rendering, so crafted item content becomes executable HTML. Exploitation requires an authenticated attacker to place a malicious task item in an issue or pull request and another user to render it; the injected script then runs in that user’s browser session.

The record

CVE
CVE-2026-2266
Published
Mar 10, 2026
Updated
Mar 10, 2026
Vendor
Twitter
Product
GitHub Enterprise Server
Classifications
CWE-79, T1189
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 10, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=3.18.0 <=3.18.5 changes=[{"at":"3.18.6","status":"unaffected"}]
  2. Affected versionversion=3.19.0 <=3.19.2 changes=[{"at":"3.19.3","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Twitter · GitHub Enterprise Serverversion=3.18.0 <=3.18.5 changes=[{"at":"3.18.6","status":"unaffected"}]; version=3.19.0 <=3.19.2 changes=[{"at":"3.19.3","status":"unaffected"}]

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
7.4GitHubCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

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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