The group-4 finding: JavaScript is callback-heavy, so the method containing a
sink routinely is not the labeled function. `fs.readFileSync` inside the
callback passed to `fs.stat` has enclosing method `<lambda>0`, and filtering on
`sinkMethod == function` dropped it -- the whole path family measured 0/8.
Scope is now decided by line-range containment within the same file
(astParentFullName is empty for lambdas, so nesting is not readable there), and
reported as `inLabeledScope`; the Python side trusts that flag and keeps the
name comparison only as a fallback, so an engine that cannot report scope never
has its sinks silently treated as scoped. Parameter sources stay bound to the
labeled function's OWN parameters -- a callback's `err`/`stats` are not
attacker input.
Fixing the scope exposed three further bugs, each of which would have raised
the number while making the answer untrue:
* Shortest-flow-wins picked the wrong witness. With closures in scope the
same sink has flows from `req.url...` (10 steps, the vulnerability), `res`
(3) and `this` (7). A flow whose source matches the source model now
outranks a shorter one from a bare captured name; shortest still breaks
ties, so the order stays total and the verdict deterministic.
* The JS fact file had NO sanitizers at all, so no JavaScript fix of any
family could ever be recognised. Added the documented path-normalisation
and HTML-escaping APIs, with provenance.
* Adding them regressed the witness, because `resolveUrl` CONTAINS `resolve`
and the substring test marked the vulnerable flow sanitized. This is the
same bug class already fixed in dominance.sc and not carried across -- the
exact fix-the-instance-miss-the-class failure. taint.sc now matches on word
boundaries too.
And the principled rule the fix turns on: parameter sources are a FALLBACK,
never an override. When a modelled source reaches the sink, those flows are the
evidence; otherwise a captured `res` reaching a sanitized sink reports the fix
as still vulnerable on a flow that names no attacker input.
Also recorded: req.url was NOT wrong as a diagnosis, it was untestable in
isolation -- the scoping bug masked it. Both were needed. On the pair that
motivated all of this:
vuln model_entailed req.url.split('?')[0] -> readFileSync(possibleFilename)
fixed model_corroborated same flow, sanitized by path.normalize
distinguished: true
700 passing, mypy/ruff clean, gates byte-identical.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG
4.1 is the arbiter for the class no crash oracle reaches. An access-control bug
is the ABSENCE of a guard: no flow to follow, no crash to reproduce. What the
model can establish is a consistency violation -- an obligated operation no
discharging guard governs, in a file where its siblings are governed by one.
"Governed" turned out not to be one relation, and asking pure CFG dominance of
the operation gets two of three shapes wrong. Measured against the real engine:
identity constraint the guard is INSIDE the operation's arguments
filter_by(owner_id = current_user.id)
identity branch abort(403).controlledBy == [note.owner_id != current_user.id]
-- the check runs AFTER the fetch, so it never dominates
the operation, but it controls whether the value escapes
dominating guard a discharger-naming call that dominates the operation
That is why the query uses controlledBy rather than dominatedBy for shape 2.
Two bugs found by running it, both the same class as the sanitizer bug in group
2 -- part of a fact flattened, the part carrying the signal dropped:
* dominance_specs used only `calls` and `decorators`, omitting
identity_sources (current_user, request.user) and constraint_params
(owner_id, user_id) -- which is how an identity constraint is actually
written. The arbiter reported "no guard" on handlers that plainly had one.
request_sources and permissive_values stay excluded: they describe the
vulnerable shape, and including them would let the arbiter read a bug as
its own fix.
* matching operations by code containment yielded four or five desugared rows
per operation (the bare `tmp1.filter_by` receiver among them, carrying none
of the guards the real call has), so a guarded operation could be flagged.
Matching is by call name now.
Live, deterministic, zero model calls:
leaky -> model_entailed no discharging guard, while 2 sibling handlers are guarded
edit_note -> no finding (ownership check controls the denial)
list_notes -> no finding (identity constraint in the query)
4.2 authors the sink facts the go/no-go measured as its largest miss class (11
of 23): Django ORM raw SQL, and the four families that previously had no fact
routing to them by CWE at all -- path, output_encoding, untrusted_destination,
prototype. Each entry is a documented dangerous API of the named library with
its provenance recorded inline, and rule_ids left empty because a sink fact is
not a detection rule. Flagged for maintainer review as data, given the standing
"no LLM-authored patterns" constraint. The exact-set assertion written in task
1.1 to hold this gap open is updated rather than deleted, so it still fails if a
family ever loses its seed.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG
Regex inventory stays the proposer. MAP attaches promote/demote/unadjudicated/coverage
from intra-file taint (tree-sitter when a grammar parses, Python ast as last resort).
Deep sandboxes promotions only, ordered by the existing heuristic ranker plus optional
OpenRouter mechanism recall. The SAST pair slice scores overlay outcomes; the stage-1
detection gate and local pair gate stay inventory-only.
Marius Ciepluch