CVE-2026-48991
XianYuLauncher: Legacy Microsoft account OAuth sign-in flow lacks PKCE and state validation
Description
XianYuLauncher is a Minecraft Java Edition launcher. In versions prior to 1.5.5, sensitive authentication artifacts could be exposed during a user-initiated login under certain local attack conditions. Affected versions relied on a fixed localhost redirect URI without PKCE or state validation. Exploitation is most likely to occur when an attacker is able to observe, intercept, or otherwise interfere with the local authentication flow on the same device. This issue has been fixed in version 1.5.5.
INFO
Published Date :
June 17, 2026, 10:16 p.m.
Last Modified :
June 22, 2026, 6:27 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update XianYuLauncher to version 1.5.5.
- Apply security patches for authentication flow.
- Validate redirect URIs and implement PKCE.
- Validate authentication state parameters.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-48991.
| URL | Resource |
|---|---|
| https://github.com/XianYuLauncher/XianYuLauncher/pull/213 | |
| https://github.com/XianYuLauncher/XianYuLauncher/security/advisories/GHSA-q6r9-qxmf-8hfx |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-48991 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-48991
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-48991 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-48991 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 18, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-48991', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-18T12:54:05.147617Z'} -
New CVE Received by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'XianYuLauncher', 'product': 'XianYuLauncher', 'versions': [{'status': 'affected', 'version': '< 1.5.5'}]}] Added Description XianYuLauncher is a Minecraft Java Edition launcher. In versions prior to 1.5.5, sensitive authentication artifacts could be exposed during a user-initiated login under certain local attack conditions. Affected versions relied on a fixed localhost redirect URI without PKCE or state validation. Exploitation is most likely to occur when an attacker is able to observe, intercept, or otherwise interfere with the local authentication flow on the same device. This issue has been fixed in version 1.5.5. Added CVSS V3.1 AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N Added CWE CWE-287 Added Reference https://github.com/XianYuLauncher/XianYuLauncher/pull/213 Added Reference https://github.com/XianYuLauncher/XianYuLauncher/security/advisories/GHSA-q6r9-qxmf-8hfx