CVE-2026-77256: sooperset mcp-atlassian · Incorrect Permissions
Affects sooperset mcp-atlassianSource CVE Database V5
Not known to be exploited · CVSS 8.3 High : upgrade to 0.22.0 soon.
Data as of 5 Nov 2026, 23:24 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 28% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 0.22.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:NExploitation 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.
What to do
Upgrade mcp-atlassian and sooperset/mcp-atlassian to 0.22.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| soopersetmcp-atlassian | Affected
| Fixed in
|
GitHubsooperset/mcp-atlassianpkg:github/sooperset/mcp-atlassianOther threats | Affected
| Fixed in
|
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 local user permissions and ensure the process umask is set to a restrictive value to prevent unauthorized users from reading the OAuth fallback file. Patch status is confirmed fixed in version 0.22.0.
Description
CVE-2026-77256 is a vulnerability in sooperset's MCP Atlassian server affecting versions prior to 0.22.0. The issue involves incorrect permission assignment for a plaintext OAuth fallback file containing refresh and access tokens. Due to permissions inherited from the process umask, other local users may read this file under common or permissive configurations, potentially allowing unauthorized access to Atlassian products. The vulnerability is fixed in version 0.22.0.
References
- github.com/sooperset/mcp-atlassian/security/advisories/GHSA-76pr-5669-3xf5 (opens in a new tab)
- github.com/sooperset/mcp-atlassian/pull/1448 (opens in a new tab)
- github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 (opens in a new tab)
- github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 (opens in a new tab)