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High, CVSS 8.3amended

MCP Atlassian: HTTP upload tools accept arbitrary server-local file paths

CVE-2026-77257GHSA-mrq8-fv7v-hhjg

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (mcp-atlassian 0.22.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N · score source
EPSS
  • CVE-2026-77257: 0.39% estimated exploitation activity in the next 30 days; percentile 32.75 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

sooperset/mcp-atlassian: HTTP upload tools can attach arbitrary server-local files Date: 2026-05-05 Target: sooperset/mcp-atlassian Commit: d8bc78698a63cb6b321c7ca796d6329d448f7f6d Summary mcp-atlassian supports HTTP/SSE deployment for persistent, remote, and multi-user use. In that mode, write-capable Jira and Confluence attachment flows accept caller-controlled server-local file paths and read those paths without an upload-source allowlist or base directory restriction. An authenticated caller, or a prompt-injected agent with tool-call capability, can cause the MCP server process to read a local file it can access and attach that file into a Jira issue or Confluence page using configured Atlassian credentials. This is distinct from the prior download-path advisory: that issue was an arbitrary file write sink. This path is upload-source local file disclosure. Impact Impact is local file disclosure through an authenticated Atlassian attachment write. In Docker/Kubernetes deployments…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-mrq8-fv7v-hhjg

  2. Revision 3 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 2 · amended ·

    Amended from osv record GHSA-mrq8-fv7v-hhjg

  4. Revision 1 · created ·

    Published from ghsa record GHSA-mrq8-fv7v-hhjg

Agent brief

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# Patch Next advisory brief: CVE-2026-77257

Advisory: MCP Atlassian: HTTP upload tools accept arbitrary server-local file paths
IDs: CVE-2026-77257, GHSA-mrq8-fv7v-hhjg
Record: https://patchnext.com/advisories/cve-2026-77257 (revision 4, source checked 26 Oct 2026, 13:54 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mcp-atlassian 0.22.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI mcp-atlassian: affected < 0.22.0; fixed in 0.22.0

## Suggested inspection (read-only)
- `python -m pip show mcp-atlassian`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mcp-atlassian.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-mrq8-fv7v-hhjg (GitHub-reviewed advisory GHSA-mrq8-fv7v-hhjg lists affected ranges: PyPI mcp-atlassian >=0 <0.22.0)
- Verified: https://osv.dev/vulnerability/GHSA-mrq8-fv7v-hhjg (OSV record GHSA-mrq8-fv7v-hhjg lists affected ranges: PyPI mcp-atlassian >=0 <0.22.0 (fixed))

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