CVE-2026-70554: MaxSite CMS contains a PHP object injection vulnerability that allows unauthenticated attackers to execute arb

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CRITICAL 9.8REMOTE

CVE-2026-70554 is a critical-severity flaw (CVSS 9.8) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

MaxSite CMS contains a PHP object injection vulnerability that allows unauthenticated attackers to execute arbitrary code by passing attacker-controlled serialized data in the maxsite_comuser cookie directly to unserialize() without validation or class allowlisting. Attackers can craft a malicious serialized PHP object payload delivered in a single HTTP request to trigger magic methods during object graph reconstruction, enabling property-oriente

Why this priority

Critical severity
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.2% (top 31%)
CISA exploited list	No
Weakness	CWE-502
Published	2026-08-04
Last modified	2026-10-23

Publisher (CNA): VulnCheck

Timeline

2026-08-04 21:16 UTCPublished CVE record published
2026-10-23 21:10 UTCUpdated Record last modified

Exact fixes by distribution

Fedora 46 · pspp · FIXED · 2.1.3-2.fc46 · FEDORA-2026-0d6444911b · source

sudo dnf upgrade --advisory=FEDORA-2026-0d6444911b

Fedora ELN · barman · FIXED · 3.20.1-3.eln159 · FEDORA-2026-45ecf042c2 · source

sudo dnf upgrade --advisory=FEDORA-2026-45ecf042c2

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Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

References

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