major vulnerability· requires attention

Enables remote code execution via module overwrite in integrations used by Atlassian Confluence/Jira, impacting many enterprise deployments.

Applications

CVE-2026-77271

8.3

High

EPSS 0.60%Patch available

mcp-atlassian arbitrary write allows module overwrite and remote code execution.

exploited

Public proof of concept per CISA SSVC; not in CISA KEV

fix

Patch available see the advisory in the references

likelihood

EPSS 0.60%top 52% of scored CVEs

Published 22 Sept 2026Analysed here 24 Sept 2026CVSS scored by the publisher (CNA)

common questions

Is CVE-2026-77271 being exploited?

Not confirmed. CVE-2026-77271 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.60% probability of exploitation in the next 30 days.

How severe is CVE-2026-77271?

CVE-2026-77271 is rated High with a CVSS score of 8.3. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2026-77271?

Yes. A fix has been recorded for CVE-2026-77271. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2026-77271 affect?

CVE-2026-77271 affects mcp-atlassian (<0.22.0), Atlassian Confluence integrations, Atlassian Jira integrations, Deployments using mcp-atlassian. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

What should I do about CVE-2026-77271?

Upgrade mcp-atlassian to >=0.22.0 and restrict upload/base_dir usage

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

executive summary

technical analysis

affected

mcp-atlassian (<0.22.0)Atlassian Confluence integrationsAtlassian Jira integrationsDeployments using mcp-atlassian

impact

Attacker-controlled attachment write can overwrite Python modules in app working dir, leading to remote code execution when imported.

action required

Immediate action required

affected versions

sooperset mcp-atlassian

affected< 0.22.0

As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.

cisa ssvc

exploitation: poc
automatable: no
technical impact: partial

Assessed by CISA 24 Sept 2026 (SSVC 2.0.3).

timeline

22 Sept 2026Published
24 Sept 2026Analysed by vulneraibility.com · 2 days later
24 Sept 2026CISA SSVC assessment: exploitation poc · same day later
24 Sept 2026CVE record last updated · same day later

also known as

GHSA-6vmq-24h2-pj7j PYSEC-2026-4087

how to fix

Remediation steps are tailored for users whose stack is affected. Add this technology to your stack to see the fix checklist.

references

NVD CVE.org CVE Details Source

4 references in the CVE record: 4 links

Linkgithub.com /sooperset/mcp-atlassian/security/advisories/GHSA-6vmq-24h2-pj7j
Linkgithub.com /sooperset/mcp-atlassian/pull/1448
Linkgithub.com /sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460
Linkgithub.com /sooperset/mcp-atlassian/releases/tag/v0.22.0

sources

CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
NVD: CVSS and CPE data
CISA Vulnrichment (ADP): SSVC decision points
FIRST EPSS: exploit probability and percentile
OSV: advisory aliases and downstream package versions
Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.

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