fix(comark): make renderMarkdown round-trips safe against injection - #376
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atinux wants to merge 6 commits into
Open
fix(comark): make renderMarkdown round-trips safe against injection#376atinux wants to merge 6 commits into
atinux wants to merge 6 commits into
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pre, mermaid, and YAML attribute blocks picked a fixed 3-backtick fence (switching to tildes only when the content contained backticks). Code containing a ~~~ line closed the fence early on re-parse, turning inert code into live document structure (e.g. ::alert components) — and the same applied to mermaid content and YAML props blocks. Add pickFence(): scan the content for the longest line-start run of each fence character and emit the shorter side, one character longer than any run present. Also stop growing mermaid content by a blank line per round trip.
comarkAttributes emitted string values as key="value" with no escaping, so a value containing a double quote closed the attribute on re-parse and the remainder became new attacker-chosen attributes (or a binding resolving frontmatter data). The props parser does not unescape backslashes, so prefer single quotes when the value has none; fall back to \"-escaping when both quote kinds are present.
A text node holding ::alert{...} (from an escaped or entity-encoded
source) was emitted verbatim by renderMarkdown, so a re-parse turned
literal text into a live component invocation; a bare :: line inside a
block component also closed the fence early.
escapeLeadingBlock now escapes lines starting with ':', and
escapeInline escapes ':' that can start an inline component (after
whitespace/start/*/_/[, before a name character) and '{' that opens an
attribute block.
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What
Three serializer hardening fixes (one commit each):
pickFence()chooses code fences that the content cannot close (pre, mermaid, YAML props blocks),comarkAttributeskeeps double quotes inside values inert, and text-node escaping now covers the Comark markers::/{.Why
A security scan found that inert content could become live structure after a documented parse →
renderMarkdown→ re-parse cycle: code containing a~~~line or mermaid content containing ``` broke out of its fence into live::alertmarkup, an attribute value with a double quote injected new attributes on re-parse, and text holding `::alert{...}` (from escaped or entity-encoded sources) re-parsed into a real component invocation. The quoting fix prefers single quotes because the props parser does not unescape backslashes.Known limitation: block math (
$$…$$) has no alternative delimiter, so math content containing$$still cannot round-trip — out of scope here.🤖 Prepared by an AI agent (OpenCode) from a security-audit findings list; commits are signed by the repository owner's key.