Reference page — cumulative record through Saturday, October 3, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-77265

CVE-2026-77265HIGH

sooperset mcp-atlassian — MCP Atlassian: SSRF via DNS Rebinding in Header-Based Authentication Flow

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   N  U  H  N  N    7.5   .0027   17.5     —

AFFECTED
  Product        Versions    Fixed
  mcp-atlassian  < 0.22.0 –  —

TIMELINE
  Aug 20  Reserved by GitHub_M
  Sep 22  Published (CNA: GitHub_M)
  Sep 29  EXPLOIT PUBLISHED — CVE-2026-77265 (sooperset mcp-atlassian). Public exploit reference added.
  Sep 29  RESCORED — CVE-2026-77265 (sooperset mcp-atlassian). CVSS 5.9 → 7.5 (NVD).

CWE-918 · CNA: GitHub_M · CVSS v3.1 · 4 references · NVD status: Analyzed

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, header-supplied Jira or Confluence URLs are resolved and validated before the HTTP client resolves the hostname again for the connection. An unauthenticated caller can use a DNS-rebinding hostname that returns a public address during validation and an internal address during connection, causing requests to internal or metadata services. The advisory traces the vulnerable input and processing flow through X-Atlassian-Jira-Url, X-Atlassian-Confluence-Url, validate_url_for_ssrf, and DNS rebinding, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

Lifecycle

Complete event history — 4 events, chronological
Date	Event	Detail
August 20, 2026	Reserved	Reserved by GitHub_M
September 22, 2026	Published	Published (CNA: GitHub_M)
September 29, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-77265 (sooperset mcp-atlassian). Public exploit reference added.
September 29, 2026	RESCORED	RESCORED — CVE-2026-77265 (sooperset mcp-atlassian). CVSS 5.9 → 7.5 (NVD).

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
sooperset	mcp-atlassian	—	< 0.22.0	—

Weaknesses

CWE-918

References (4)

https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 [Patch]
https://github.com/sooperset/mcp-atlassian/pull/1448 [Issue Tracking, Patch]
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 [Release Notes]
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-49xv-9743-pw8w [Exploit, Vendor Advisory]

Authoritative record: CVE-2026-77265 at cve.org

Vendors: sooperset

Weaknesses: CWE-918

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-77265 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Saturday, October 3, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.