VulnerabilityPublished 22 Sep 2026

CVE-2026-77250: sooperset mcp-atlassian · Cleartext Storage of Sensitive Information

Affects sooperset mcp-atlassianSource CVE Database V5

Compare

Not known to be exploited · CVSS 6.1 Medium : upgrade to 0.22.0 when convenient.

Data as of 5 Nov 2026, 00:01 UTC

CVSS 3.1 base score

6.1Medium

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 1% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.22.0

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

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: Low
Availability: None

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

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
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 22 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
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 5 Nov 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 0.22.0.

Affected software

Product	Affected	Fixed in
soopersetmcp-atlassian	Affected <0.22.0	Fixed in 0.22.0
GitHubsooperset/mcp-atlassian`pkg:github/sooperset/mcp-atlassian`Other threats	Affected <0.22.0	Fixed in 0.22.0

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

AI-suggested

Upgrade mcp-atlassian to version 0.22.0 or later, where the issue is fixed. Until then, restrict file permissions on the ~/.mcp-atlassian directory and its contents to prevent unauthorized local access. Review and rotate any potentially exposed OAuth tokens to prevent misuse.

Description

CVE-2026-77250 is a vulnerability in sooperset's mcp-atlassian server prior to version 0.22.0 where OAuthConfig stores access and refresh tokens in cleartext files under the user's .mcp-atlassian directory. On systems with permissive file permissions, other local users or processes can read these tokens and potentially reuse them to access Atlassian services. This issue is fixed in version 0.22.0.

Impact

The vulnerability allows local attackers with access to the user's home directory to read OAuth access and refresh tokens stored in plaintext. This can lead to unauthorized access to Atlassian services associated with the compromised tokens. The CVSS 3.1 score is 6.1 (medium severity), reflecting local attack vector with low complexity and no user interaction required, resulting in high confidentiality impact but limited integrity and no availability impact.

Summary

The vulnerability involves cleartext storage of sensitive OAuth tokens by the mcp-atlassian server's OAuthConfig component before version 0.22.0. Specifically, the tokens are written to plaintext fallback files named ~/.mcp-atlassian/oauth-<client_id>.json with default process permissions. If the system's umask is permissive, other users in the same group or other local users can read these files and gain unauthorized access to Atlassian resources by reusing the tokens. The flaw is tracked as CWE-312 and was addressed by updating the token storage method in version 0.22.0.

CWE-312Cleartext Storage of Sensitive Information (opens in a new tab)
Base weaknessOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product stores sensitive information in cleartext within a resource that might be accessible to another control sphere.
Implementation · System Configuration · Operation
When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to encrypt the data at rest.
Implementation · System Configuration · Operation
In some systems/environments such as cloud, the use of "double encryption" (at both the software and hardware layer) might be required, and the developer might be solely responsible for both layers, instead of shared responsibility with the administrator of the broader system/environment.
OWASP Cheat Sheets
Secure Design Principles (opens in a new tab)
OWASP ASVS 4.0.3
V8.1.6 (opens in a new tab)
V8.2.3 (opens in a new tab)
V8.2.2 (opens in a new tab)
Attack patterns
Retrieve Embedded Sensitive Data (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 29 Sep 2026, 20:49 UTC

WeaknessesCWE-312

Technical details

References

Community reviews

Related threats