GHSA-PCC4-RVHR-2PR8
Vulnerability from github – Published: 2026-10-19 16:51 – Updated: 2026-10-19 16:52Summary
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:
- Absolute includes —
#include "/etc/passwd"is opened directly by cpp. - 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 <file>), 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 cleanly; high-entropy case-sensitive blobs (base64/JWT) are partially corrupted by the lower-casing but still confirm readability and structure. Single-token-per-line secret files (API-key files, single-line credential/token files) leak that token in full (lower-cased). Requires cpp/gcc on PATH (near-ubiquitous on the dev/CI hosts graphify targets); it cleanly falls back to raw bytes when absent.
Suggested fix
Mirror the containment approach already used elsewhere in the codebase (_project_xml_is_safe, security.validate_graph_path): before invoking cpp, scan the source for #include directives and refuse or neutralise any include whose target is absolute or resolves outside the corpus/repo root. Concretely, in _cpp_preprocess:
- Parse
#include "..."/#include <...>directives. - Resolve each target against the file's directory; if it is absolute, or its
.resolve()escapes the scan root, strip that line (or fall back topath.read_bytes()with no preprocessing). - Only allow includes that resolve to a path inside the corpus root.
A blunter but safe alternative is to strip all #include lines before preprocessing (macros still expand; cross-file includes lose fidelity but no host files can be read). Running cpp inside a filesystem sandbox (bwrap/unshare with only the corpus mounted) would also close it but is heavier.
Detected by
Aeon vuln-scanner. Semgrep flagged the Fortran subprocess path; manual review of the F-007 mitigation plus an empirical cpp repro confirmed the bypass.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "graphifyy"
},
"ranges": [
{
"events": [
{
"introduced": "0.7.2"
},
{
"fixed": "0.9.70"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-73"
],
"github_reviewed": true,
"github_reviewed_at": "2026-10-19T16:51:36Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "## Summary\n\nThe Fortran extractor\u0027s 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).\n\nThis is the exact \"corpus-side file-exfiltration vector\" the F-007 comment says it is defending against; the mitigation is bypassable.\n\n## Severity\n\nHigh. Arbitrary local-file read on the host, triggered by graphify\u0027s core action (indexing an untrusted folder \u2014 \"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`) \u2014 no credentials, network, or LLM call required. CWE-73 (external control of file name/path) / CWE-22 (path traversal) / CWE-200 (information exposure).\n\n## Where\n\n`graphify/extractors/fortran.py`, `_cpp_preprocess()`:\n\n result = subprocess.run(\n [\"cpp\", \"-w\", \"-P\", \"-nostdinc\", \"-I\", \"/dev/null\", str(path.resolve())],\n capture_output=True, timeout=30,\n )\n\nReached 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`.\n\n## Why the mitigation does not work\n\n`-nostdinc` only removes the standard *system* include directories, and `-I /dev/null` only sets the *additional* search path. Neither affects:\n\n1. Absolute includes \u2014 `#include \"/etc/passwd\"` is opened directly by cpp.\n2. Quoted includes relative to the current file \u2014 cpp always searches the directory containing the file being preprocessed for `#include \"...\"`, so `#include \"../../../../etc/shadow\"` traverses out of the corpus.\n\n## Proof of concept (verified)\n\nReproduced against the shipped code with the exact command `_cpp_preprocess` builds (`cpp -w -P -nostdinc -I /dev/null \u003cfile\u003e`), and against `extract_fortran()` directly.\n\nSecret on disk (`/tmp/secret.txt`): `TOP_SECRET_...`\n\n(a) Absolute include \u2014 `evil_abs.F90`:\n\n program evil\n #include \"/absolute/path/to/secret.txt\"\n end program evil\n\n(b) Relative traversal \u2014 `evil_rel.F90`:\n\n program evil\n #include \"../secret.txt\"\n end program evil\n\nBoth produce preprocessed output containing the full secret file contents (`\"SECRET IN OUTPUT: True\"` for both).\n\nSurfacing into the graph \u2014 `leak.F90` places the include in an identifier position via a free-form continuation so the leaked value becomes a node/edge:\n\n module m\n contains\n subroutine s\n use \u0026\n #include \"/path/to/token.secret\"\n end subroutine s\n end module m\n\n`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 \u2014 i.e. exfiltrated into the agent\u0027s context and into persisted, shareable artifacts.\n\nFidelity 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 cleanly; high-entropy case-sensitive blobs (base64/JWT) are partially corrupted by the lower-casing but still confirm readability and structure. Single-token-per-line secret files (API-key files, single-line credential/token files) leak that token in full (lower-cased). Requires `cpp`/gcc on PATH (near-ubiquitous on the dev/CI hosts graphify targets); it cleanly falls back to raw bytes when absent.\n\n## Suggested fix\n\nMirror the containment approach already used elsewhere in the codebase (`_project_xml_is_safe`, `security.validate_graph_path`): before invoking cpp, scan the source for `#include` directives and **refuse or neutralise any include whose target is absolute or resolves outside the corpus/repo root**. Concretely, in `_cpp_preprocess`:\n\n- Parse `#include \"...\"` / `#include \u003c...\u003e` directives.\n- Resolve each target against the file\u0027s directory; if it is absolute, or its `.resolve()` escapes the scan root, strip that line (or fall back to `path.read_bytes()` with no preprocessing).\n- Only allow includes that resolve to a path inside the corpus root.\n\nA blunter but safe alternative is to strip all `#include` lines before preprocessing (macros still expand; cross-file includes lose fidelity but no host files can be read). Running cpp inside a filesystem sandbox (bwrap/unshare with only the corpus mounted) would also close it but is heavier.\n\n## Detected by\n\nAeon vuln-scanner. Semgrep flagged the Fortran subprocess path; manual review of the F-007 mitigation plus an empirical `cpp` repro confirmed the bypass.",
"id": "GHSA-pcc4-rvhr-2pr8",
"modified": "2026-10-19T16:52:23Z",
"published": "2026-10-19T16:51:36Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Graphify-Labs/graphify/security/advisories/GHSA-pcc4-rvhr-2pr8"
},
{
"type": "WEB",
"url": "https://github.com/Graphify-Labs/graphify/commit/e1d9deed6a437f2c85458ef3c42519159f322b7b"
},
{
"type": "PACKAGE",
"url": "https://github.com/Graphify-Labs/graphify"
},
{
"type": "WEB",
"url": "https://github.com/Graphify-Labs/graphify/releases/tag/v0.9.70"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Graphify Fortran extractor: incomplete cpp #include hardening allows arbitrary host-file read/exfiltration when indexing an untrusted repo"
}
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