CVE-2026-77138 Remote Code Execution in extension "HTML5 Video Player vs. Powermail" (html5videoplayer_powermail)
Remote unauthenticated attackers can achieve code execution on TYPO3 servers by sending crafted serialized payloads via cookies to the HTML5 Video Player extension.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-77138?
CVE-2026-77138 is a critical unsafe deserialization vulnerability in TYPO3 Extension "HTML5 Video Player vs. Powermail", published on 25 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
The extension fails to safely process untrusted client input of an attacker-controlled cookie directly to PHP's unserialize(). A remote, unauthenticated attacker can supply a crafted serialized payload to trigger PHP Object Injection, leading to Remote Code Execution on the TYPO3 server.
Weakness: CWE-502
Which versions are affected by CVE-2026-77138?
How do I fix CVE-2026-77138?
No fix has been published for CVE-2026-77138 yet. Limit exposure of the affected software until one is available.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-77138 being exploited?
There is no known exploitation of CVE-2026-77138 in the wild and no public exploit code.
Sources
Also known as GHSA-mj2c-4qfw-rhhc.