CVE-2026-48991 json
XianYuLauncher: Legacy Microsoft account OAuth sign-in flow lacks PKCE and state validation
published 4mo ago modified 4mo ago also EUVD-2026-37808
- cvss
- 5.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.1%
- EPSS 0.1% chance of exploitation in 30 days, percentile 2%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- github.com/XianYuLauncher/XianYuLauncher#213 pull request
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Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 4mo ago
Exploit prediction
0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-11).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 5.5 | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N |
Affected products
- XianYuLauncher XianYuLauncher
Classification
- Weakness
-
- CWE-287 Improper Authentication
References
Sources
- CVE List CVE-2026-48991
- NVD CVE-2026-48991
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