CVE-2026-77257

HIGHPre-NVD 8.38.3—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 68% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
8.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.3Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, HTTP-exposed Jira and Confluence upload tools pass a caller-provided file_path to local file operations without restricting it to the workspace. A remote MCP caller with tool access can cause the server to read sensitive local files and upload them as Atlassian attachments. The advisory traces the vulnerable input and processing flow through streamable-http, upload_attachment, and file_path, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

CVSS v3
8.3
EG Score
8.3(medium)
EG Risk
38(Track)
EG Risk 38/100SSVC: Track

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
Severity83% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
32%
KEV
Not listed

Published

September 22, 2026

Last Modified

September 23, 2026

Advisory Details (4)

Auto-updated Sep 22, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_pr, github_commit, github_release.
github_release Patch Available

v0.22.0

Patch available: sooperset/mcp-atlassian v0.22.0

https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0
github_commit Patch Available

commit b041733473f9 (sooperset/mcp-atlassian)

Patch available: sooperset/mcp-atlassian v0.22.0 (contains commit b041733473f9)

https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460
github_pr Patch Available

Security hardening across attachment, transport, SSRF, authorization, filter, and OAuth layers

Patch available: sooperset/mcp-atlassian v0.22.0 (PR #1448 merged 2026-07-10)

https://github.com/sooperset/mcp-atlassian/pull/1448
github Patch Available🟡 PoC Available

HTTP upload tools accept arbitrary server-local file paths · Advisory · sooperset/mcp-atlassian · GitHub

https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-mrq8-fv7v-hhjg

Vendor Advisories for CVE-2026-77257(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
mcp-atlassian0.1.1 ... 0.9.0 (79 versions)0.22.0—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 9× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-09-24 16:46 UTCEG score recompute
  2. 2026-09-24 14:04 UTCEPSS rescore
  3. 2026-09-23 18:26 UTCEG score recompute
  4. 2026-09-23 17:54 UTCEPSS rescore
  5. 2026-09-23 15:20 UTCEG score recompute
  6. 2026-09-23 14:50 UTCEG score recompute
  7. 2026-09-22 19:37 UTCEG score recompute
  8. 2026-09-22 18:33 UTCEG score recompute
  9. 2026-09-22 18:33 UTCMITRE cvelistV5first tracked

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-77257?
CVE-2026-77257 is a high vulnerability published on September 22, 2026. MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, HTTP-exposed Jira and Confluence upload tools pass a caller-provided filepath to local file operations without restricting it to the workspace. A remote MCP caller with tool access…
When was CVE-2026-77257 disclosed?
CVE-2026-77257 was first published in the National Vulnerability Database on September 22, 2026, with the most recent update on September 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-77257 actively exploited?
CVE-2026-77257 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 68.1% of all scored CVEs.
What is the CVSS score of CVE-2026-77257?
CVE-2026-77257 has a CVSS v3 base score of 8.3 (NVD).
How do I remediate CVE-2026-77257?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-77257, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-77257

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