Package Instance

symfony/validator XML Entity Expansion vulnerability
Symfony 2.0.11 carried a [similar] XXE security fix, however, on review of ZF2 I also noted a vulnerability to XML Entity Expansion (XEE) attacks whereby all extensions making use of libxml2 have no defense against XEE Quadratic Blowup Attacks. The vulnerability is a function of there being no current method of disabling custom entities in PHP (i.e. defined internal to the XML document without using external entities). In a QBA, a long entity can be defined and then referred to multiple times in document elements, creating a memory sink with which Denial Of Service attacks against a host's RAM can be mounted. The use of the LIBXML_NOENT or equivalent option in a dependent extension amplified the impact (it doesn't actually mean "No Entities"). In addition, libxml2's innate defense against the related Exponential or Billion Laugh's XEE attacks is active only so long as the LIBXML_PARSEHUGE is NOT set (it disables libxml2's hardcoded entity recursion limit). No instances of these two options were noted, but it's worth referencing for the future.

Consider this (non-fatal) example:
```
<?xml version="1.0"?>
<!DOCTYPE data [<!ENTITY a
"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa">]>
<data>&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;&a;</data>
```
Increase the length of entity, and entity count to a few hundred, and peak memory usage will waste no time spiking the moment the nodeValue for is accessed since the entities will then be expanded by a simple multiplier effect. No external entities required.

...

This can be used in combination with the usual XXE defense of calling libxml_disable_entity_loader(TRUE) and, optionally, the LIBXML_NONET option (should local filesystem access be allowable). The DOCTYPE may be removed instead of rejecting the XML outright but this would likely result in other problems with the unresolved entities. "

If you cannot upgrade to the latest Symfony version, you can also apply this [patch](https://github.com/symfony/symfony/compare/352e8f583c87c709de197bb16c4053d2e87fd4cd...5bf4f92e86c34690d71e8f94350ec975909a435b.diff).

Symfony has an incorrect response from Validator when input ends with `\n`
### Description

It is possible to trick a `Validator` configured with a regular expression using the `$` metacharacters, with an input ending with `\n`.

### Resolution

Symfony now uses the `D` regex modifier to match the entire input.

The patch for this issue is available [here](https://github.com/symfony/symfony/commit/7d1032bbead9a4229b32fa6ebca32681c80cb76f) for branch 5.4.

### Credits

We would like to thank Offscript for reporting the issue and Alexandre Daubois for providing the fix.

Symfony collectionCascaded and collectionCascadedDeeply fields security bypass
When using the Validator component, if `Symfony\\Component\\Validator\\Mapping\\Cache\\ApcCache` is enabled (or any other cache implementing `Symfony\\Component\\Validator\\Mapping\\Cache\\CacheInterface`), some information is lost during serialization (the `collectionCascaded` and the `collectionCascadedDeeply` fields).

As a consequence, arrays or traversable objects stored in fields using the `@Valid` constraint are not traversed by the validator as soon as the validator configuration is loaded from the cache.

Improper Restriction of XML External Entity Reference
Security fixes related to the way XML is handled in symfony.