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Advisory record · GHSA-wv8v-v4c5-v75j

MCP Atlassian: MCP HTTP Client Server-Local File Exfiltration via Unvalidated Attachment Upload Path

CVSS 7.4 HighEPSS 0.0047 · 40th percentile

Published by the GitHub Advisory Database at 22 Sept 2026, 20:34 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
mcp-atlassianPyPI<0.22.00.22.0
Identifiers
GHSA-wv8v-v4c5-v75j · CVE-2026-77246 · PYSEC-2026-4104
Weakness (CWE)
CWE-22 · CWE-200 · CWE-441
Tags
Published
22 Sept 2026
Updated
1 Oct 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Versions of mcp-atlassian before 0.22.0 are affected. When the server runs in HTTP transport mode with write tools enabled (READ_ONLY_MODE not set to true, which is the default), an unauthenticated remote attacker can supply their own Atlassian service URL and token headers. They can then use the attachment upload tool to send any file readable by the server process to an endpoint they control. Upgrade to mcp-atlassian 0.22.0 or later. Setting READ_ONLY_MODE=true reduces exposure, though the source does not describe it as a complete fix.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
7.4 High 3.1 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0047, the 40th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:09 UTC First seen by agentprime
  2. 31 Oct 2026, 14:09 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.