VulnerabilityPublished 10 Mar 2026

CVE-2026-27826: sooperset mcp-atlassian · Server-Side Request Forgery (SSRF)

Affects sooperset mcp-atlassianSource CVE Database V5

Compare

Not known to be exploited · public detection template (Nuclei) · 13% EPSS · CVSS 8.2 High : upgrade to 0.17.0 soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

8.2High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 13.0% chance of exploitation in 30 days – higher than 96% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.17.0

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N

Attack Vector: Adjacent
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Changed
Confidentiality: High
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Adjacent: The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Mar 2026
Detectable: evidence found.
nuclei template: mcp-atlassian < 0.17.0 - Server-Side Request Forgery
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade mcp-atlassian and sooperset/mcp-atlassian to 0.17.0.

Affected software

Product	Affected	Fixed in
soopersetmcp-atlassian	Affected <0.17.0	Fixed in 0.17.0
GitHubsooperset/mcp-atlassian`pkg:github/sooperset/mcp-atlassian`Other threats	Affected <0.17.0	Fixed in 0.17.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Organizations should immediately upgrade all instances of mcp-atlassian to version 0.17.0 or later, where this SSRF vulnerability is fixed. Until upgrades can be applied, network-level mitigations should be implemented: restrict access to the mcp-atlassian HTTP endpoint to trusted internal IP addresses only, using firewalls or network segmentation. Employ egress filtering to prevent unauthorized outbound HTTP requests from the server, especially blocking access to sensitive internal IP ranges such as the cloud instance metadata service (169.254.169.254). Monitor network traffic for unusual outbound requests originating from mcp-atlassian servers. Implement strict input validation and header inspection at the HTTP middleware layer if possible, to detect and block suspicious custom headers that could trigger SSRF. Conduct internal network scans to identify any exposed mcp-atlassian endpoints and remediate accordingly. Review and audit IAM role permissions to minimize the impact of potential credential theft. Finally, monitor logs and LLM tool outputs for signs of injection or poisoning attempts that may indicate exploitation.

Description

CVE-2026-27826 is a high-severity Server-Side Request Forgery (SSRF) vulnerability in sooperset's mcp-atlassian server versions prior to 0.17.0. It allows unauthenticated attackers who can access the HTTP endpoint to force the server to make arbitrary outbound HTTP requests by supplying two custom headers without needing an Authorization header. This vulnerability resides in the HTTP middleware and dependency injection layer, bypassing tool-level code detection. In cloud environments, it can lead to theft of IAM role credentials via the instance metadata service. In any deployment, it enables internal network reconnaissance and injection of attacker-controlled content into LLM tool results. The issue is fixed in version 0.17.0.

Impact

The primary impact of CVE-2026-27826 is the unauthorized ability for attackers to make the vulnerable server perform arbitrary HTTP requests, which can lead to significant security breaches. In cloud environments, attackers can exploit this SSRF to access the instance metadata service, potentially stealing IAM credentials that grant elevated privileges, enabling further compromise of cloud infrastructure and data exfiltration. In on-premises or private network deployments, the vulnerability facilitates internal network reconnaissance, allowing attackers to map internal services and potentially identify further vulnerabilities. Additionally, attackers can inject malicious content into the responses processed by LLM tools, potentially poisoning outputs and misleading users or automated processes relying on these tools. The lack of authentication and user interaction requirements increases the likelihood of exploitation once network access is obtained. Organizations using Atlassian products integrated with mcp-atlassian servers prior to version 0.17.0 face risks of data confidentiality breaches, integrity violations, and potential lateral movement within their networks. The vulnerability could also undermine trust in LLM-based tools by corrupting their data inputs.

CWE-918Server-Side Request Forgery (opens in a new tab)
Base weaknessCWE Top 25 (2025): #22OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
Implementation · Operation
If there is a known list of applications, IP, hostname, and/or domains to which the product is allowed to communicate, then use allowlists to ensure that outgoing requests are restricted to these known entities. The allowlists could be in the application code or possibly enforced by firewalls or network segmentation.
Implementation · Operation
If the product is expected to be able to connect to arbitrary IP addresses or domains, consider using a denylist that includes private network addresses, internal domain names, etc. The denylist could be in the application code or possibly enforced by firewalls or network segmentation.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
OWASP Cheat Sheets
Server Side Request Forgery Prevention (opens in a new tab)
Unvalidated Redirects and Forwards (opens in a new tab)
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V12.6.1 (opens in a new tab)
V5.2.6 (opens in a new tab)
Attack patterns
Server Side Request Forgery (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Mar 2026, 19:28 UTC

Public exploits and detectiona Nuclei detection template

WeaknessesCWE-918

Technical details

References

Community reviews

Related threats