# Set JSON parser policy for UTF-8, duplicate names, and nonstandard extensions > Use RFC 8259 — The JavaScript Object Notation (JSON) Data Interchange Format to review this narrow operational decision without extending the source beyond its stated scope. - Canonical URL: https://update.dsesecurity.com/updates/set-json-parser-policy-for-utf-8-duplicate-names-and-nonstandard-extensions/ - Publisher: Detection Systems & Engineering (DSE Security) - Author: DSE Security Editorial Team - Published: 2026-08-27T12:15:43+00:00 - Modified: 2026-08-27T12:53:58+00:00 - Last reviewed by DSE: 2026-08-26 - Resource type: Explainer - DSE priority: Advisory - Topics: Cybersecurity, Networks & Infrastructure - Reading time: 3 minutes ## What you need to know Use RFC 8259 — The JavaScript Object Notation (JSON) Data Interchange Format to review this narrow operational decision without extending the source beyond its stated scope. ## Potentially affected Teams, systems, services, or facilities within the stated scope of RFC 8259 — The JavaScript Object Notation (JSON) Data Interchange Format ## DSE recommendation Compare the observed state with the cited official source, document applicability and exceptions, and test any approved change with rollback safeguards. ## Article Frame this document as a source-led configuration and assurance check: Set JSON parser policy for UTF-8, duplicate names, and nonstandard extensions. Only the official source and traced locations below supply facts. Confirm applicability before acting. ## Source fact: The official [RFC 8259 — The JavaScript Object Notation (JSON) Data Interchange Format](https://www.rfc-editor.org/rfc/rfc8259.html) from RFC Editor / Internet Engineering Task Force supports the following bounded statements: - A JSON parser MUST accept every text that conforms to the JSON grammar and MAY accept non-JSON forms or extensions; it may also impose limits on size, nesting, numbers, and strings. The research record locates this support at Section 9 (Parsers). - JSON exchanged outside a closed ecosystem MUST use UTF-8; generators MUST NOT add a byte order mark, while parsers MAY ignore one for interoperability. The research record locates this support at Section 8.1 (Character Encoding). - Names within a JSON object SHOULD be unique because receivers handle duplicate names unpredictably, including keeping only the last pair, rejecting the object, or exposing every pair. The research record locates this support at Section 4 (Objects). The source support ends with the statements listed above. Use them to examine clients, origin services, intermediaries, caches, proxies, gateways, protocol versions, and security-policy enforcement points in the applicable environment, not to imply a wider guarantee. ## What the source does not establish This RFC evidence supports only the named web or transport decision; it does not prove browser, intermediary, library, or service compatibility. It does not establish a deployment’s current state, authorize a production change, prove compliance, or show that DNS, certificates, identity providers, time, content delivery, network paths, and application ownership are healthy. Documented options are review inputs, not universal mandates. ## Applicability questions - For source statement 1 at Section 9 (Parsers), which observable configuration, record, or test can confirm applicability here? - For source statement 2 at Section 8.1 (Character Encoding), which observable configuration, record, or test can confirm applicability here? - For source statement 3 at Section 4 (Objects), which observable configuration, record, or test can confirm applicability here? - What inventory proves which parts of clients, origin services, intermediaries, caches, proxies, gateways, protocol versions, and security-policy enforcement points are in and out of scope? - Which condition in DNS, certificates, identity providers, time, content delivery, network paths, and application ownership must be healthy before evidence is trustworthy? - What result would disprove the working assumption and return the issue to the owner? ## DSE recommendation: DSE recommends using the cited source as the evidence anchor for this decision. Make the source, asset scope, owner, and expected outcome explicit in the review record. Record the source location, examined part of clients, origin services, intermediaries, caches, proxies, gateways, protocol versions, and security-policy enforcement points, observed and expected states, owner, and reason for deviation. Translate the conclusion into change control only after documenting dependencies, impact, test method, expected signals, failure signals, and restoration steps. Include DNS, certificates, identity providers, time, content delivery, network paths, and application ownership, while excluding secrets and sensitive personal or topology data from ordinary tickets. ## Verification and evidence Tie each conclusion back to Section 9 (Parsers); Section 8.1 (Character Encoding); Section 4 (Objects) and to observable material such as request and response captures, negotiated protocol details, headers, cache behavior, certificate state, and server or proxy logs. Preserve provenance and stable identifiers without copying secrets into the evidence set. Retain the starting state, authorization, execution record, outcome, deviation, and final state as one review package. Move disruptive checks to an approved test path. Reopen the decision when versions, design, dependencies, ownership, or official guidance changes. ## Official references - [RFC 8259 — The JavaScript Object Notation (JSON) Data Interchange Format](https://www.rfc-editor.org/rfc/rfc8259.html) — RFC Editor / Internet Engineering Task Force ## Primary reference - Name: RFC 8259 — The JavaScript Object Notation (JSON) Data Interchange Format - Authority: www.rfc-editor.org - URL: https://www.rfc-editor.org/rfc/rfc8259.html - Source publication date: Not stated by the source ## Citation and use Preferred citation: “Set JSON parser policy for UTF-8, duplicate names, and nonstandard extensions,” DSE Security, https://update.dsesecurity.com/updates/set-json-parser-policy-for-utf-8-duplicate-names-and-nonstandard-extensions/ Publishing principles: https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/ Usage and citation policy: https://update.dsesecurity.com/usage/ Copyright © 2026 Detection Systems & Engineering. 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