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.
CVE-2026-48991
MEDIUMPre-NVD 5.55.5—
EchelonGraph scoreMEDIUM confidence
This medium-severity CVE scores 5.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 97% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, secondary
5.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.5Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 5.5
- EG Score
- 5.5(medium)
- EPSS
- 2.7%
- KEV
- Not listed
Published
June 17, 2026
Last Modified
June 22, 2026
Advisory Details (2)
Auto-updated Jun 17, 2026Patch available. Sources: github_pr, github.
github Patch Available
Legacy Microsoft account OAuth sign-in flow lacks PKCE and state validation · Advisory · XianYuLauncher/XianYuLauncher · GitHub
https://github.com/XianYuLauncher/XianYuLauncher/security/advisories/GHSA-q6r9-qxmf-8hfxgithub_pr
fix: msal oauth hardening
Fix merged in XianYuLauncher/XianYuLauncher PR #213 on 2026-05-17 — awaiting tagged release
https://github.com/XianYuLauncher/XianYuLauncher/pull/213Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-48991?
CVE-2026-48991 is a medium vulnerability published on June 17, 2026. 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.…
When was CVE-2026-48991 disclosed?
CVE-2026-48991 was first published in the National Vulnerability Database on June 17, 2026, with the most recent update on June 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-48991 actively exploited?
CVE-2026-48991 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-48991?
CVE-2026-48991 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2026-48991?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-48991, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-48991
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