Vulnerability Database

361,925

Total vulnerabilities in the database

Grav has Insecure Deserialization in File Cache — getgrav / grav

Deserialization of Untrusted Data

Insecure Deserialization in File Cache

  • Severity: High
  • CWE: CWE-502
  • Location: system/src/Grav/Framework/Cache/Adapter/FileCache.php
  • Sink: unserialize($value, ['allowed_classes' => true])

Affected version(s)

  • Affected: >= 1.7.44 and <= 1.7.49.5 (verified in current codebase and changelog-covered releases).
  • Fixed: No upstream fix identified in the reviewed branch at the time of analysis.
  • Notes: Earlier 1.7.x releases may also be affected, but were not fully back-traced in this review.

Notes

allowed_classes => true allows object instantiation and does not constrain classes.

PoC (Primitive Demonstration)

Preconditions

  • Local PHP runtime.
  • Goal is to validate the deserialization primitive used in cache retrieval.

Steps

php -r ' class CacheWakeup { public function __wakeup(){ file_put_contents("/tmp/grav_filecache_poc.txt", "wakeup"); } } $payload = serialize(new CacheWakeup()); unserialize($payload, ["allowed_classes" => true]); echo file_exists("/tmp/grav_filecache_poc.txt") ? "FILECACHE_UNSERIALIZE_TRIGGERED\n" : "FILECACHE_UNSERIALIZE_NOT_TRIGGERED\n"; '

Expected Result

  • Output contains: FILECACHE_UNSERIALIZE_TRIGGERED.

Interpretation

This reproduces the same unsafe primitive used by FileCache::doGet(): unserialize($value, ['allowed_classes' => true]). If cache files are attacker-tampered, object magic methods may execute.

Exploit Preconditions

  • Cache file poisoning/tampering capability.

Recommendation

  • Avoid object deserialization in cache payloads.
  • Use non-object formats and integrity protection for cache files.

Maintainer note — fix applied (2026-04-24)

Fixed in Grav core on the 2.0 branch: commit c66dfeb5f — will ship in 2.0.0-beta.2.

What changed: Framework\Cache\Adapter\FileCache now HMAC-signs every cache payload with Security::getNonceKey() on write, and verifies the HMAC on read. Tampered, forged, or pre-upgrade files are treated as cache misses and unlinked instead of being unserialized. The on-disk format is now versioned:

v2 <expires> <key> <hmac-hex> <serialized>

Existing caches rebuild transparently on first read. Note that Framework\Cache\Adapter\FileCache isn't wired into Grav's main cache path — Symfony's FilesystemAdapter is — but the class is reachable by plugin and downstream consumers, so the hardening applies defensively.

Files:

  • Published: May 5, 2026
  • Updated: May 6, 2026
  • GHSA: GHSA-gwfr-jfjf-92vv
  • Severity: High
  • Exploit:
  • CISA KEV:

No technical information available.

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