Medium [CVE-2026-59876] Prototype pollution vulnerability in Text Format extension
This medium-severity Red Hat Linux advisory covers CVE-2026-59876 affecting Red Hat Ceph Storage 9.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published Record updated
Summary
protobufjs compiles protobuf definitions into JavaScript (JS) functions. From 8.2.0 until 8.6.5, the protobufjs Text Format extension parsed string-keyed map entries using ordinary property assignment, allowing a map entry with key __proto__ to change the prototype of the returned map object instead of creating an own map entry in protobufjs/ext/textformat.
This issue is fixed in version 8.6.5. A flaw was found in protobufjs.
An attacker could exploit this to alter object behavior, potentially leading to information disclosure or other impacts. This Moderate-impact flaw in protobufjs allows an attacker to perform prototype pollution by providing specially crafted input to the Text Format extension.
Red Hat severity: Moderate — CVSS 4.8 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N). Weakness: CWE-915.
Affected Red Hat products: Red Hat Ceph Storage 9.
Red Hat lists Cryostat 4; OpenShift Pipelines; OpenShift Service Mesh 3; Red Hat Ansible Automation Platform 2; Red Hat Build of Podman Desktop; Red Hat Developer Hub; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux AI (RHEL AI) 3; Red Hat Hardened Images; Red Hat OpenShift Container Platform 4; Red Hat Openshift Data Foundation 4; Self-service automation portal 2 as not affected.
Red Hat does not currently list a fixing RHSA for this CVE.
Is CVE-2026-59876 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-59876 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-59876?
Upgrade to a fixed release named by Red Hat:
- 8.6.5
Confirm against the vendor advisory before you patch.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
Mitigation checklist
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
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