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.
- 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
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.
Which versions are affected by CVE-2026-8612?
It affects 1 product.
Products include Oalders Www\.
How do I fix CVE-2026-8612?
Upgrade to a fixed version.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-8612 being exploited?
There is no known exploitation of CVE-2026-8612 in the wild and no public exploit code.
Sources
Also known as GHSA-38r9-g25v-vcvr, MGASA-2026-0149.