GHSA-88fw-v6x4-3f58

`src/main/java/org/springframework/data/mapping/context/PersistentPropertyPathFactory.java:175` · Unbounded Resource Allocation (Algorithmic DoS)

### Impact

When a consuming module routes user-supplied dot-paths (sort parameters, projection paths, PATCH paths) through `MappingContext.getPersistentPropertyPath(String, Class)`, each distinct string — including invalid ones — is cached forever. A remote attacker can send millions of requests with unique `?sort=aaaa<n>` values and grow the heap until the service OOMs.

### Description

`PersistentPropertyPathFactory.propertyPaths` (line 53) is a `ConcurrentHashMap<TypeAndPath, PathResolution>` populated by `getPotentiallyCachedPath()` (line 174-177) via `computeIfAbsent`. The key is `(TypeInformation, rawPathString)`. Crucially, unresolvable paths are also cached (as `PathResolution.unresolved`, line 204) so that the same `InvalidPersistentPropertyPath` can be re-thrown — meaning every distinct garbage string an attacker sends creates a permanent entry. There is no eviction. This is reachable from `AbstractMappingContext.getPersistentPropertyPath(String, Class)` (`AbstractMappingContext.java:345`), which Spring Data REST and several store query mappers call with HTTP-request-derived sort/filter property names.

By contrast, the sibling `SimplePropertyPath.cache` was already hardened to use `ConcurrentReferenceHashMap` (soft refs); this cache was not given the same treatment.

### Exploit scenario

Against a Spring Data REST endpoint, an attacker scripts `GET /things?sort=<random-40-char-string>` in a loop. Each request fails fast with `InvalidPersistentPropertyPath`, but each distinct random string leaves behind a `TypeAndPath` key, a `PathResolution` object holding the split segments list, and the source string in the map. After ~10M requests the JVM OOMs.

### Preconditions

- A downstream component (Spring Data REST, a store-specific `QueryMapper`, or application code) passes externally-supplied strings to `MappingContext.getPersistentPropertyPath(String, ...)` - No upstream rate-limiting or path-string validation

### How to fix

A cache whose key can be derived from external input must be bounded. Replace `propertyPaths` (line 53) with a `ConcurrentLruCache<TypeAndPath, PathResolution>` of fixed capacity, or `ConcurrentReferenceHashMap` (matching the sibling `SimplePropertyPath.cache`). Additionally, do not cache `PathResolution.unresolved` results at all (line 204 in `createPersistentPropertyPath`) — re-computing a failed lookup is cheap, and caching negative results for arbitrary attacker strings is what makes this exploitable.

### Adversarial verification

**Verdict:** TRUE_POSITIVE (confidence: 7/10) — unbounded hard-ref `ConcurrentHashMap` keyed by raw path string, caches unresolved entries (line 204), reachable via public `MappingContext.getPersistentPropertyPath(String, ...)`; sibling `PropertyPath` cache was already converted to soft-refs but this one was missed. -3 confidence because the HTTP-input wiring lives in downstream modules (Spring Data REST / store mappers), not verifiable in this repo.

**Code at the line — CONFIRMED** - Line 53: `private final Map<TypeAndPath, PathResolution> propertyPaths = new ConcurrentHashMap<>();` — plain CHM, hard refs, no eviction, no size bound. - Line 175: `propertyPaths.computeIfAbsent(TypeAndPath.of(type, propertyPath), ...)` — every distinct `(type, string)` pair is inserted. - Line 204: `return PathResolution.unresolved(parts, segment, type, currentPath);` — returned from inside `computeIfAbsent`'s mapping function, so unresolvable paths are cached. The `PathResolution` retains the full attacker string (`source = StringUtils.collectionToDelimitedString(parts, ".")`, line 452).

**Callers within spring-data-commons** - `AbstractMappingContext.getPersistentPropertyPath(String, Class<?>)` (line 345) and `(String, TypeInformation<?>)` (line 350) → `persistentPropertyPathFactory.from(type, propertyPath)` → straight into the unbounded cache. No validation, no `PropertyPath.from` gate. - This is the public `MappingContext` interface (`MappingContext.java:174,186`), documented to throw `InvalidPersistentPropertyPath` on bad input — i.e., the contract explicitly anticipates being called with possibly-invalid strings. - No in-repo caller routes HTTP input directly into the `String` overload. The `Sort.Order.property` → `getPersistentPropertyPath(String, ...)` bridge lives in store modules (Spring Data MongoDB `QueryMapper`, Spring Data REST sort translator). That wiring is out-of-repo as the finding states.

**Protections — NONE on this cache** Contrast: `SimplePropertyPath.java:52` (the `PropertyPath.from` cache) uses `ConcurrentReferenceHashMap` (soft refs, GC-evictable). Spring already hardened the sibling cache against exactly this pattern. `PersistentPropertyPathFactory.propertyPaths` was not given the same treatment.

**Stress-test** Is this exclusion #3 (intended design)? The `PathResolution` javadoc (line 426-430) says caching unresolved paths is deliberate — to make repeated lookups of the *same* bad path cheap. But unbounded hard-ref caching of *arbitrary attacker-chosen* keys is not the intent; the sibling fix proves Spring considers this a bug class.