MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, upload_attachment in src/mcp_atlassian/confluence/attachments.py accepts a caller-controlled file_path and opens the selected server-local file without restricting it to the workspace. A permitted Confluence MCP caller can upload the file as an attachment and disclose data readable by the server process. This issue is fixed in version 0.22.0.
CVE-2026-77258
HIGHPre-NVD 7.77.7—Trending — 3 sources updated this week
EchelonGraph scoreMEDIUM confidence
This high-severity CVE scores 7.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 59% 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
7.7EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.7Exploit: None knownExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.7
- EG Score
- 7.7(medium)
- EG Risk
- 39(Track)EG Risk 39/100SSVC: 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 computedSeverity77% × 45%Exploitation0% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 41%
- 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/v0.22.0github_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/b041733473f95119dd539542a43c280737a8e460github_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/1448github Patch Available🟡 PoC Available
Arbitrary file read/exfiltration via upload_attachment missing validate_safe_path() · Advisory · sooperset/mcp-atlassian · GitHub
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-93xw-j965-9mx3Vendor Advisories for CVE-2026-77258(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)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| mcp-atlassian | 0.1.1 ... 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 5× in last 7d / 5× 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.
- 2026-09-23 18:37 UTCEG score recompute
- 2026-09-23 17:54 UTCEPSS rescore
- 2026-09-22 18:32 UTCEG score recompute
- 2026-09-22 17:48 UTCEG score recompute
- 2026-09-22 17:48 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Same CWE
10 shownCWE-22
- CVE-2026-85706EG 10.0 KEVEPSS p95CRITICAL
- CVE-2026-82954EG 9.9CRITICAL
- CVE-2026-8859EG 9.9CRITICAL
- CVE-2026-9559EG 9.9CRITICAL
- CVE-2026-96276EG 9.8CRITICAL
- CVE-2026-93616EG 9.8 KEVCRITICAL
- CVE-2026-89040EG 9.8CRITICAL
- CVE-2026-85661EG 9.8CRITICAL
- CVE-2026-82460EG 9.8CRITICAL
- CVE-2026-9181NVD 7.5EG 9.8CRITICAL
Frequently asked(5)
What is CVE-2026-77258?
CVE-2026-77258 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, uploadattachment in src/mcpatlassian/confluence/attachments.py accepts a caller-controlled file_path and opens the selected server-local file without restricting it to the…
When was CVE-2026-77258 disclosed?
CVE-2026-77258 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-2026-77258 actively exploited?
CVE-2026-77258 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 59.4% of all scored CVEs.
What is the CVSS score of CVE-2026-77258?
CVE-2026-77258 has a CVSS v3 base score of 7.7 (NVD).
How do I remediate CVE-2026-77258?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-77258, 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-2026-77258
Is Your Infrastructure Affected by CVE-2026-77258?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.