CVE-2026-48991

MEDIUMPre-NVD 5.55.5
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This medium-severity CVE scores 5.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2% (7th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
5.5EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 5.5Exploit: None knownExposed services: Not assessed

The CVE record names the fixed release — apply it.

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.

CVSS v3
5.5
EG Score
5.5MEDIUMmedium confidence
EG Risk
25
EG Risk 25/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed (value × EchelonGraph’s weight)
Severity55% × 45%
The EG Score, 5.5 of 10.
Exploitation0.2% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: The CVE record names the fixed release. Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
7th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

The CVE record names the fixed release. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

June 17, 2026

Last Modified

June 22, 2026

Advisory Details (2)

Auto-updated Jun 17, 2026
Fix named in the CVE record. Sources: github_pr, github.
GitHub advisoryMentions a patch (unverified)

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-8hfx
GitHub pull request

fix: msal oauth hardening

Fix merged in XianYuLauncher/XianYuLauncher PR #213 on 2026-05-17 — awaiting tagged release

https://github.com/XianYuLauncher/XianYuLauncher/pull/213

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 28× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 137 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 37 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.2% · 7th percentile
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  17. 2026-10-02 16:40 UTCOSV refresh
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  1. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
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Frequently asked(5)

What is CVE-2026-48991?
CVE-2026-48991 is a medium-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-48991 published?
The CVE record for CVE-2026-48991 was published on June 17, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of June 22, 2026; the record at its source may have been updated since.
Is CVE-2026-48991 actively exploited?
CVE-2026-48991 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (7th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-48991?
CVE-2026-48991 has a CVSS base score of 5.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-48991?
The CVE record for CVE-2026-48991 names the fix: "This issue has been fixed in version 1.5.5."

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