YAML safe_load production fallback to unsafe_load enables RCE via deserialization

published 2026-10-12 28 d ago modified 2026-10-14 25 d ago also EUVD-2026-97362

cvss: 8.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 39%
public exploits: 0; none known

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.

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-52903 updated 2026-06-28 cvss 8.8

manageiq: YAML safe_load production fallback to unsafe_load enables RCE via deserialization

Red Hat All currently supported Red Hat products
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 25 d ago (2026-10-14)

Exploit prediction

0.45% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

ManageIQ ManageIQ
Red Hat Red Hat CloudForms

Classification

Weakness

CWE-502 Deserialization of Untrusted Data

References

Sources

CVE List CVE-2026-52903
NVD CVE-2026-52903

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Summary