CVE-2026-52903 YAML safe_load production fallback to unsafe_load enables RCE via deserialization
Authenticated attackers can achieve remote code execution in ManageIQ by uploading crafted YAML payloads that trigger unsafe deserialization fallbacks.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-52903?
CVE-2026-52903 is a high-severity unsafe deserialization vulnerability in ManageIQ, published on 12 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
A deserialization of untrusted data vulnerability was found in ManageIQ. The YamlLoadAliases module overrides YAML.safe_load to silently fall back to YAML.unsafe_load in production when a Psych::DisallowedClass error occurs. An authenticated attacker with dialog import access can exploit this to achieve remote code execution by uploading a crafted YAML payload that triggers the fallback and deserializes arbitrary Ruby objects.
Red Hat CloudForms, which was based on ManageIQ, has reached End of Life and is no longer supported. No errata or patches will be issued. This CVE is being assigned for the benefit of the ManageIQ community and downstream consumers.
Weakness: CWE-502
Which versions are affected by CVE-2026-52903?
How do I fix CVE-2026-52903?
No fix has been published for CVE-2026-52903 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-2026-52903 being exploited?
There is no known exploitation of CVE-2026-52903 in the wild and no public exploit code.
Sources
Also known as GHSA-rwm4-fgr7-vcr6.