CVE-2026-77272

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the OAuth error query parameter is passed to CallbackHandler._send_response in oauth_setup.py and interpolated into an HTML page without escaping. A crafted authorization callback can inject markup or script that executes in the browser of a user completing the OAuth flow. This issue is fixed in version 0.22.0.

Overview

State: PUBLISHED
Assigner (CNA): GitHub_M
CVSS severity: MEDIUM
CVSS score: 5.4 / 10
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Effective score: 5.4 / 10 MEDIUM source: CNA overview
CWE(s): CWE-79
Reserved: 2026-08-20
Published: 2026-09-22 18:33 UTC
Last updated: 2026-09-22 18:33 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/77xxx/CVE-2026-77272.json

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-09-22 19:16:51 UTC
NVD last modified: 2026-09-22 19:16:51 UTC
NVD CVSS v3.1: 5.4 / 10 MEDIUM source: security-advisories@github.com
NVD CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Exploitability subscore: 2.8 / 10
Impact subscore: 2.5 / 10

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-84749
Assigner: GitHub_M
Published: Sep 22, 2026, 6:33:18 PM
Updated: Sep 22, 2026, 6:33:18 PM
EUVD base score (CVSS 3.1): 5.4 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
EUVD-reported EPSS: 0.0000
Vendors: sooperset
Products: mcp-atlassian (< 0.22.0)
Aliases: GHSA-g2r2-3j32-j27x

ENISA description: MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the OAuth error query parameter is passed to CallbackHandler._send_response in oauth_setup.py and interpolated into an HTML page without escaping. A crafted authorization callback can inject markup or script that executes in the browser of a user completing the OAuth flow. This issue is fixed in version 0.22.0.

EUVD references (4)

Affected products (1)

Vendor	Product	Versions	Platforms
sooperset	mcp-atlassian	`< 0.22.0` (affected)	—

Vendor references (4)

References embedded in the original CVE record by the assigning CNA.

https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g2r2-3j32-j27x x_refsource_CONFIRM
https://github.com/sooperset/mcp-atlassian/pull/1448 x_refsource_MISC
https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 x_refsource_MISC
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 x_refsource_MISC

Web references (0)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

No web references attached yet.

NVD-tagged references (4)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 security-advisories@github.com
https://github.com/sooperset/mcp-atlassian/pull/1448 security-advisories@github.com
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 security-advisories@github.com
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g2r2-3j32-j27x security-advisories@github.com

Remediations (10)

CVE-2026-20272 - Vulnerability Details - OpenCVE

web:app.opencve.io

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco IOS XE Software engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE - 2026 -20272 are related to issues with improper neutralization of ...

2026-09-23 15:44 UTC
Nvd-cve-2026-20272

web:nvd.nist.gov

Description As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco IOS XE Software engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE - 2026 -20272 are related to issues with improper ...

2026-09-23 15:44 UTC
Cisco Advance Notification for Publication of September 16, 2026 ...

web:sec.cloudapps.cisco.com

On September 16, 2026 , the Cisco Product Security Incident Response Team (PSIRT) published the advisories that are listed in the following tables. To remediate these vulnerabilities, Cisco strongly recommends that customers upgrade to the fixed software that is indicated in the advisories. For more information about changes in Cisco PSIRT vulnerability disclosure, see Strengthening the ...

2026-09-23 15:44 UTC
Microsoft Patch Tracker (September 2026): Exploit-Ranked | Senserva

web:senserva.com

Every Microsoft security patch (KB) and the CVEs it fixes, with severity, CVSS, and CISA KEV status. Cross-linked to the CVE reference.

2026-09-23 15:44 UTC
About the security content of iOS 26.6 and iPadOS 26.6

web:support.apple.com

This document describes the security content of iOS 26.6 and iPadOS 26.6.

2026-09-23 15:44 UTC
September 8, 2026—KB5122878 (OS Builds 19045.7725 and 19044.7725 ...

web:support.microsoft.com

This security update includes fixes and quality improvements that are part of the following updates: August 11, 2026—KB5120249 (OS Builds 19045.7663 and 19044.7663) The following is a summary of the issues that this update addresses when you install this update. If there are new features, it lists them as well. The bold text within the brackets indicates the item or area of the change we are ...

2026-09-23 15:44 UTC
SAP Security Patch Day - June 2026

web:support.sap.com

SAP security Patch Day Bulletin This post shares the information on security notes that remediate vulnerabilities discovered in SAP products. SAP strongly recommends that the customer visits the support portal and applies patches on priority to protect their SAP landscape. On 9th of June 2026 , SAP security patch day saw the release of 15 new security notes.

2026-09-23 15:44 UTC
SAP Security Patch Day - September 2026

web:support.sap.com

SAP Security Patch Day Bulletin This post shares the information on security notes that remediate vulnerabilities discovered in SAP products. SAP strongly recommends that the customer visits the support portal and applies patches on priority to protect their SAP landscape. On 8 th of September 2026 , SAP security patch day saw the release of 19 new security notes. There is 1 update to ...

2026-09-23 15:44 UTC
Oracle Critical Patch Update Advisory - July 2026

web:www.oracle.com

This Critical Patch Update contains 1448 new security patches across the product families listed below. Please note that a My Oracle Support (MOS) note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at July 2026 Critical Patch Update: Executive Summary and Analysis.

2026-09-23 15:44 UTC
CVE-2026-20272 - Critical Vulnerability - TheHackerWire

web:www.thehackerwire.com

How do I fix or mitigate CVE - 2026 -20272? To protect against CVE - 2026 -20272, you should: (1) Apply the latest security patches from Cisco, (2) Check official security advisories for specific remediation steps, (3) Update affected software to the latest version, and (4) Monitor your systems for any signs of exploitation.

2026-09-23 15:44 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-77272.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "mcp-atlassian",
          "vendor": "sooperset",
          "versions": [
            {
              "status": "affected",
              "version": "< 0.22.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the OAuth error query parameter is passed to CallbackHandler._send_response in oauth_setup.py and interpolated into an HTML page without escaping. A crafted authorization callback can inject markup or script that executes in the browser of a user completing the OAuth flow. This issue is fixed in version 0.22.0."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.4,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-79",
              "description": "CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-22T18:33:18.421Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g2r2-3j32-j27x",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g2r2-3j32-j27x"
        },
        {
          "name": "https://github.com/sooperset/mcp-atlassian/pull/1448",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/sooperset/mcp-atlassian/pull/1448"
        },
        {
          "name": "https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460"
        },
        {
          "name": "https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0"
        }
      ],
      "source": {
        "advisory": "GHSA-g2r2-3j32-j27x",
        "discovery": "UNKNOWN"
      },
      "title": "MCP Atlassian: Reflected XSS in OAuth Setup Callback Handler"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-77272",
    "datePublished": "2026-09-22T18:33:18.421Z",
    "dateReserved": "2026-08-20T19:14:21.330Z",
    "dateUpdated": "2026-09-22T18:33:18.421Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}