UNDF: UNDF-2026-000000314

UNDF: (pending)

tinkerpop-0001: MutablePath.isSimple — missing O(P) override, falls back to O(P²) default

CWE-407 — Algorithmic Complexity

Field	Value
ID	tinkerpop-0001
Severity	MEDIUM
Ecosystem	tinkerpop
Package	gremlin-core
File	`gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/util/MutablePath.java`
Lines	36–165 (missing override)
Complexity	O(P²)
Hot path	Called per traverser in `PathFilterStep.filter()` when `.simplePath().by(...)` or `.cyclicPath().by(...)` is used

Defect

MutablePath does not override isSimple(). The default implementation in Path.java uses a nested double-loop over objects():

// Path.java default — O(P²)
public default boolean isSimple() {
    final List<Object> objects = this.objects();
    for (int i = 0; i < objects.size() - 1; i++) {
        for (int j = i + 1; j < objects.size(); j++) {
            if (Objects.equals(objects.get(i), objects.get(j)))
                return false;
        }
    }
    return true;
}

ImmutablePath already has the correct O(P) override using a HashSet:

// ImmutablePath — O(P) ✓
public boolean isSimple() {
    final Set<Object> objects = new HashSet<>();
    ImmutablePath currentPath = this;
    while (true) {
        if (currentPath.isTail()) return true;
        else if (objects.contains(currentPath.currentObject)) return false;
        else { objects.add(currentPath.currentObject); currentPath = currentPath.previousPath; }
    }
}

MutablePath is used in PathFilterStep.filter() (line 65) and PathStep (line 119) when a by() modulator is present. byPath.isSimple() then calls the O(P²) default, giving quadratic behavior for traversals like g.V().simplePath().by(...) with long paths.

Fix

Add the O(P) override to MutablePath:

// MutablePath.java — add this override
@Override
public boolean isSimple() {
    final Set<Object> seenObjects = new HashSet<>();
    for (final Object object : this.objects) {
        if (!seenObjects.add(object)) {
            return false;
        }
    }
    return true;
}

Speedup

P (path length)	Before (comparisons)	After (comparisons)	Speedup
10	45	10	4.5×
50	1,225	50	24.5×
100	4,950	100	49.5×
500	124,750	500	249.5×

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