# GHSA-xg9w-r469-m455: ZendFramework Potential Information Disclosure and Insufficient Entropy vulnerabilities

> Predictable random number generation in Zend Framework allows attackers to recover seeds, disclose information, and bypass CSRF protections.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 7 Jun 2024

## What is GHSA-xg9w-r469-m455?

GHSA-xg9w-r469-m455 is a vulnerability in zendframework/zendframework, published on 7 Jun 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In Zend Framework 2, the `Zend\Math\Rand` component generates random bytes using the OpenSSL or Mcrypt extensions when available but will otherwise use PHP's `mt_rand()` function as a fallback. All outputs from `mt_rand()` are predictable for the same PHP process if an attacker can brute force the seed used by the Marsenne-Twister algorithm in a Seed Recovery Attack. This attack can be successfully applied with minimum effort if the attacker has access to either a random number from `mt_rand()` or a Session ID generated without using additional entropy. This makes `mt_rand()` unsuitable for generating non-trivial random bytes since it has Insufficient Entropy to protect against brute force attacks on the seed.

The `Zend\Validate\Csrf` component generates CSRF tokens by SHA1 hashing a salt, random number possibly generated using `mt_rand()` and a form name. Where the salt is known, an attacker can brute force the SHA1 hash with minimum effort to discover the random number when `mt_rand()` is utilised as a fallback to the OpenSSL and Mcrypt extensions. This constitutes an Information Disclosure where the recovered random number may itself be brute forced to recover the seed value and predict the output of other `mt_rand()` calls for the same PHP process. This may potentially lead to vulnerabilities in areas of an application where `mt_rand()` calls exist beyond the scope of Zend Framework.

## Which versions are affected by GHSA-xg9w-r469-m455?

4 open source packages ship an affected version, including zendframework/zendframework.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `zendframework/zendframework` | Packagist | From 2.0.0 | 2.0.8 |
| `zendframework/zendframework` | Packagist | From 2.0.0 | 2.0.8 |
| `zendframework/zendframework` | Packagist | From 2.1.0 | 2.1.4 |
| `zendframework/zendframework` | Packagist | From 2.1.0 | 2.1.4 |

## How do I fix GHSA-xg9w-r469-m455?

Upgrade zendframework/zendframework to a fixed version for your release line: 2.0.8 or 2.1.4.

## Is GHSA-xg9w-r469-m455 being exploited?

There is no known exploitation of GHSA-xg9w-r469-m455 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-xg9w-r469-m455 and fix it if it is affected.

What it is: GHSA-xg9w-r469-m455 is a vulnerability in zendframework/zendframework, published on 7 Jun 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of GHSA-xg9w-r469-m455 in the wild and no public exploit code.

Affected packages and fixed versions:
- zendframework/zendframework (Packagist): affected from 2.0.0; fixed in 2.0.8
- zendframework/zendframework (Packagist): affected from 2.0.0; fixed in 2.0.8
- zendframework/zendframework (Packagist): affected from 2.1.0; fixed in 2.1.4
- zendframework/zendframework (Packagist): affected from 2.1.0; fixed in 2.1.4

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/GHSA-xg9w-r469-m455/ (Markdown: https://insights.sbomify.com/GHSA-xg9w-r469-m455/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-xg9w-r469-m455

---
From sbomify Insights: https://insights.sbomify.com/GHSA-xg9w-r469-m455/
Summaries are generated and may contain mistakes; the official description above is the record.