Prevent path traversal in git resolver pathInRepo parameter
Committed by vdemeester
fix: prevent path traversal in git resolver pathInRepo parameter
The git resolver's pathInRepo parameter was not validated for path
traversal, allowing a tenant to read arbitrary files from the resolver
pod's filesystem by supplying paths like '../../../../etc/passwd' or
'../../../../var/run/secrets/kubernetes.io/serviceaccount/token'.
The resolved file contents were then written into
resolutionrequest.status.data (base64-encoded), creating an
exfiltration channel. Since the resolver pod's ServiceAccount typically
has broad RBAC permissions (including read access to secrets), this
could lead to full privilege escalation.
The fix adds two layers of defense:
1. Validate pathInRepo in PopulateDefaultParams() to reject paths
containing '..' components. Leading slashes are stripped for
backwards compatibility (filepath.Join already handles them safely).
2. Switch getFileContent() to use 'git show HEAD:<path>' to read files
from git's object store instead of os.ReadFile from the filesystem.
Symlinks are resolved via filepath.EvalSymlinks before computing the
relative path for git show, so in-repo symlinks work correctly while
escape symlinks produce paths that git show rejects.
Unit and e2e regression tests are added for traversal patterns,
symlink escapes, and valid leading-slash paths.
The vulnerability was introduced in commit 318006c4e3a5 when the git
resolver switched from go-git's in-memory filesystem (memfs) to
shelling out to git and reading files with os.ReadFile(). All releases
from v1.0.0 through v1.10.0 are affected.
Fixes: GHSA-j5q5-j9gm-2w5cEditor assessment
This commit patches CVE-2026-33211. The subject alone could carry a fix; the body is why this reads as exemplar material, reconstructing the vulnerability from input to impact with traversal strings, the status-data exfiltration path and the RBAC-amplified escalation. Rather than listing patches, it explains the two defense layers and their trade-off: rejecting `..` components while still stripping leading slashes so existing manifests keep resolving, and moving reads into git's object store with EvalSymlinks so escape symlinks are refused. Regression tests, the commit where the regression entered, the release exposure window and the advisory footer are all accounted for. Only the numbered list formatting is a stylistic choice.