Security readout for executives and security teams
Plain-English summary
CVE-2026-27735 affects mcp-server-git, part of the Model Context Protocol Servers reference implementations. A path validation flaw in git_add could let a user-controlled request stage files located outside the intended Git repository. This does not prove data theft by itself, but it can expose sensitive files to later commit or workflow actions.
Executive priority
Treat as a near-term patching item for teams using MCP Git automation. It is not reported as actively exploited, but it can undermine repository boundaries and expose files through normal development workflows. Prioritize environments connected to AI agents, CI/CD, or automated commits.
Technical view
Versions before 2026.1.14 allow git_add file paths that traverse outside repository boundaries. The advisory states this occurred because GitPython repo.index.add() accepted relative paths resolving outside the repository, unlike expected Git CLI behavior. The issue is classified as CWE-22 with CVSS 4.0 score 6.4.
Likely exposure
Exposure is likely where mcp-server-git versions earlier than 2026.1.14 are deployed and users or agents can invoke git_add with file arguments. Risk is higher if repositories sit near sensitive files or if staged changes are automatically committed, reviewed poorly, or processed by automation.
Exploitation context
The source bundle does not indicate CISA KEV listing or active exploitation. Exploitation requires interaction with the git_add tool and suitable repository/file-system context. The main concern is unauthorized staging of files outside the repository boundary, potentially affecting downstream confidentiality or integrity.
Researcher notes
Evidence is limited to the CVE record, GitHub advisory, and linked pull request. The advisory names the vulnerable behavior and fixed version but does not provide broad deployment impact. Focus review on path-boundary validation, GitPython index behavior, and whether downstream automation could turn staging into disclosure.
Mitigation direction
- Upgrade mcp-server-git to version 2026.1.14 or newer.
- Review vendor advisory GHSA-vjqx-cfc4-9h6v for current guidance.
- Restrict who or what can invoke mcp-server-git tools.
- Avoid running MCP Git servers near unrelated sensitive files.
- Review automation that commits or publishes staged changes.
Validation and detection
- Inventory deployments using modelcontextprotocol servers mcp-server-git.
- Confirm installed versions are 2026.1.14 or newer.
- Review recent Git index changes for unexpected outside-repository file paths.
- Check CI or agent logs for unusual git_add activity.
- Verify access controls around MCP clients and tool invocation.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-22: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupFile access behavior lookup
The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-27735 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.4 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
6.4MediumVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/modelcontextprotocol/servers/security/advisories/GHSA-vjqx-cfc4-9h6vCVE reference · x_refsource_CONFIRM
- https://github.com/modelcontextprotocol/servers/pull/3164CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.