6

CVE-2026-48529: github github-mcp-server Improper Access Control

CVSS: 6.0v3.1MediumDeferred
AliasesGHSA-pjp5-fpmr-3349GO-2026-5779
Published 26-06-2026Last modified 27-06-2026
Open JSON

Vulnerability summary

CVE-2026-48529 is a medium (CVSS 6.0) Improper Access Control vulnerability in github github-mcp-server. EPSS estimates a 0.21% chance of exploitation in the next 30 days, higher than 9.9% of scored vulnerabilities.

Overall risk
24/100
0100
Low · default modelHow is this calculated?
CVSS score
6.0/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.21%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
OPENSUSE-SU-2026:21483-1

Timeline

  1. 26-06-2026
    PublishedVulnerability first disclosed.
  2. 27-06-2026
    Last modifiedVulnerability information updated.

Description

GitHub MCP Server is GitHub's official MCP Server. From 0.22.0 until 1.1.2, when running in HTTP mode with --lockdown-mode enabled, the RepoAccessCache is implemented as a process-global singleton initialized with the first authenticated user's GraphQL client. All subsequent requests from different users share this singleton and their lockdown-related GraphQL queries are executed using the first user's credentials. The singleton is never updated to reflect later users' tokens. This vulnerability is fixed in 1.1.2.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.21%

Chance of exploitation in the next 30 days

Percentile

10%

Versus all other CVEs

30-day change

0.00 pp

From 0.21% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.21%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Github1 product
Github.com/github1 product
  • github-mcp-server≥ 0.22.0, < 1.1.2

2 vendors · 2 products

References

2 links