GHSA-gwfr-jfjf-92vv CVE-2026-7317

Grav has Insecure Deserialization in File Cache

Medium Packagist

Severity: 0.0 / 10; Medium · CVSS 4.0
Exploit chance (EPSS): 0.22%; Chance of exploitation in the next 30 days. Higher than 13.06% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-20 Improper Input Validation; CWE-502 Deserialization of Untrusted Data
Fix: 2.0.0-beta.2; Upgrade getgrav/grav to this version or later

Description

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:

system/src/Grav/Framework/Cache/Adapter/FileCache.php.
tests/unit/Grav/Common/Security/FileCacheSecurityTest.php — round-trip, tampered-payload rejection, wrong-key forgery rejection, pre-v2 file rebuild, key-field mismatch.

Affected versions

Packagist

Package	Vulnerable	Fixed in
getgrav/grav	`< 2.0.0-beta.2`	`2.0.0-beta.2`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

getgrav/grav Packagist → `2.0.0-beta.2`

composer

composer require getgrav/grav:^2.0.0-beta.2

Severity breakdown

CVSS 4.0 0.0

CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

Attack vector: Network
Attack complexity: High
Attack requirements: None
Privileges required: Low
User interaction: None
Confidentiality (vulnerable system): Low
Integrity (vulnerable system): Low
Availability (vulnerable system): Low
Confidentiality (subsequent systems): None
Integrity (subsequent systems): None
Availability (subsequent systems): None
Exploit maturity: Proof of concept

CVSS 3.1 5.0

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L

Attack vector: Network
Attack complexity: High
Privileges required: Low
User interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: Low

Weakness

CWE-20: Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How to prevent it

Architecture and Design: Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build "recognizers" for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses. [REF-1109] [REF-1110] [REF-1111]
Architecture and Design: Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
Architecture and Design, Implementation: Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.
Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server. Even though client-side checks provide minimal benefits with respect to server-side security, they are still useful. First, they can support intrusion detection. If the server receives input that should have been rejected by the client, then it may be an indication of an attack. Second, client-side error-checking can provide helpful feedback to the user about the expectations for valid input. Third, there may be a reduction in server-side processing time for accidental input errors, although this is typically a small savings.
Implementation: When your application combines data from multiple sources, perform the validation after the sources have been combined. The individual data elements may pass the validation step but violate the intended restrictions after they have been combined.
Implementation: Be especially careful to validate all input when invoking code that crosses language boundaries, such as from an interpreted language to native code. This could create an unexpected interaction between the language boundaries. Ensure that you are not violating any of the expectations of the language with which you are interfacing. For example, even though Java may not be susceptible to buffer overflows, providing a large argument in a call to native code might trigger an overflow.
Implementation: Directly convert your input type into the expected data type, such as using a conversion function that translates a string into a number. After converting to the expected data type, ensure that the input's values fall within the expected range of allowable values and that multi-field consistencies are maintained.
Implementation: Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180, CWE-181). Make sure that your application does not inadvertently decode the same input twice (CWE-174). Such errors could be used to bypass allowlist schemes by introducing dangerous inputs after they have been checked. Use libraries such as the OWASP ESAPI Canonicalization control. Consider performing repeated canonicalization until your input does not change any more. This will avoid double-decoding and similar scenarios, but it might inadvertently modify inputs that are allowed to contain properly-encoded dangerous content.
Implementation: When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.

CWE-502: Deserialization of Untrusted Data

The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.