# CVE-2026-8612: Deserialization in WWW::Mechanize::Cached

> A local attacker can forge cached HTTP responses in a world-writable directory, leading to arbitrary code execution via unsafe deserialization in Perl applications.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 May 2026
- **Updated:** 15 May 2026
- **Also known as:** GHSA-38r9-g25v-vcvr, MGASA-2026-0149

## What is CVE-2026-8612?

CVE-2026-8612 is a medium-severity unsafe deserialization vulnerability in OALDERS WWW::Mechanize::Cached, published on 15 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

WWW::Mechanize::Cached versions before 2.00 for Perl deserialize cached HTTP responses from a world-writable on-disk cache, enabling local response forgery and code execution.

With no explicit cache backend, WWW::Mechanize::Cached constructs a default Cache::FileCache under /tmp/FileCache without overriding the backend's documented directory_umask of 000, so the cache root and its subdirectories are created mode 0777 with no sticky bit. Cache entries are named by sha1_hex of the request and read back through Storable::thaw on the next cache hit.

A local attacker with write access to the cache tree can replace a victim's cache entry for a known URL with an arbitrary frozen HTTP::Response blob, causing the victim's next get() of that URL to return attacker controlled response bytes. Because the bytes are passed to Storable::thaw, a victim process that has loaded any class with a side-effectful STORABLE_thaw, DESTROY, or overload hook can be escalated to arbitrary code execution.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource), CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-8612?

It affects 1 product.


Products: Oalders Www\.

## How do I fix CVE-2026-8612?

Upgrade to a fixed version.

## Is CVE-2026-8612 being exploited?

There is no known exploitation of CVE-2026-8612 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-8612 and fix it if it is affected.

What it is: CVE-2026-8612 is a medium-severity unsafe deserialization vulnerability in OALDERS WWW::Mechanize::Cached, published on 15 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-8612 in the wild and no public exploit code.

Affected product: OALDERS WWW::Mechanize::Cached. No package-level version data is available, so check the vendor advisory linked from the reference page.

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/CVE-2026-8612/ (Markdown: https://insights.sbomify.com/CVE-2026-8612/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-8612
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-8612
- OSV: https://osv.dev/vulnerability/CVE-2026-8612

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-8612/
Summaries are generated and may contain mistakes; the official description above is the record.