GHSA-pcc4-rvhr-2pr8

Graphify Fortran extractor: incomplete cpp #include hardening allows arbitrary host-file read/exfiltration when indexing an untrusted repo

Published

2026-10-19

Modified

2026-10-19

Sources

github-advisory

Summary

## Summary The Fortran extractor's C-preprocessor step (`graphify/extractors/fortran.py`, `_cpp_preprocess`) applies an incomplete `#include` hardening. The `-nostdinc -I /dev/null` flags it relies on (comment "Security (F-007)") do **not** stop a capital-`F` Fortran source file from including **absolute paths** (`#include "/etc/passwd"`) or from **path-traversing out of the corpus** (`#include "../../../../home/victim/.ssh/id_rsa"`). `cpp` always searches the directory of the file being preprocessed for quoted includes and always honours absolute include paths, regardless of `-nostdinc`/`-I`. As a result, indexing an untrusted repository that contains a `.F`/`.F90`/`.F95`/`.F03`/`.F08` file reads arbitrary local files off the host and inlines their contents into the knowledge graph, which is then shipped to the LLM/agent and written to the on-disk, shareable output (`graph.json`, `GRAPH_REPORT.md`, the Obsidian wiki, HTML/SVG exports). This is the exact "corpus-side file-exfiltration vector" the F-007 comment says it is defending against; the mitigation is bypassable. ## Severity High. Arbitrary local-file read on the host, triggered by graphify's core action (indexing an untrusted folder — "turn any folder of code ... into a queryable knowledge graph"), defeating a documented security control. It runs on the default, offline, no-API-key AST path (`graphify update .` / `graphify extract`) — no credentials, network, or LLM call required. CWE-73 (external control of file name/path) / CWE-22 (path traversal) / CWE-200 (information exposure). ## Where `graphify/extractors/fortran.py`, `_cpp_preprocess()`: result = subprocess.run( ["cpp", "-w", "-P", "-nostdinc", "-I", "/dev/null", str(path.resolve())], capture_output=True, timeout=30, ) Reached from `extract_fortran()` (same file) for any suffix in `_FORTRAN_CPP_EXTS = {".F", ".F90", ".F95", ".F03", ".F08"}`, which are collected by default (`detect.CODE_EXTENSIONS`) and dispatched by `extract._DISPATCH`. ## Why the mitigation does not work `-nostdinc` only removes the standard *system* include directories, and `-I /dev/null` only sets the *additional* search path. Neither affects: 1. Absolute includes — `#include "/etc/passwd"` is opened directly by cpp. 2. Quoted includes relative to the current file — cpp always searches the directory containing the file being preprocessed for `#include "..."`, so `#include "../../../../etc/shadow"` traverses out of the corpus. ## Proof of concept (verified) Reproduced against the shipped code with the exact command `_cpp_preprocess` builds (`cpp -w -P -nostdinc -I /dev/null `), and against `extract_fortran()` directly. Secret on disk (`/tmp/secret.txt`): `TOP_SECRET_...` (a) Absolute include — `evil_abs.F90`: program evil #include "/absolute/path/to/secret.txt" end program evil (b) Relative traversal — `evil_rel.F90`: program evil #include "../secret.txt" end program evil Both produce preprocessed output containing the full secret file contents (`"SECRET IN OUTPUT: True"` for both). Surfacing into the graph — `leak.F90` places the include in an identifier position via a free-form continuation so the leaked value becomes a node/edge: module m contains subroutine s use & #include "/path/to/token.secret" end subroutine s end module m `extract_fortran()` on this file emits a node whose label is the entire single-line contents of `token.secret` and an `imports` edge to it. That node is written to `graph.json` / `GRAPH_REPORT.md` / the wiki and returned by the MCP `query_graph` / `get_node` / `get_neighbors` tools — i.e. exfiltrated into the agent's context and into persisted, shareable artifacts. Fidelity note: Fortran is case-insensitive, so captured identifiers are lower-cased. Case-insensitive secrets (file paths, hostnames, usernames, hex tokens, connection-string fragments, and the mere existence/partial content of a readable file) leak cle

Affected packages

Remediation: Upgrade to 0.9.70 or later.

References

• https://github.com/advisories/GHSA-pcc4-rvhr-2pr8