The main branch is considered the actively supported line.

Please do not open public issues for unpatched vulnerabilities.

Report security concerns via GitHub Security Advisories (preferred).
If Security Advisories are unavailable, open a GitHub issue with minimal details and request private coordination.

Include:

• Affected component and version/commit
• Reproduction steps
• Impact assessment
• Suggested mitigation (if available)

Maintainers will acknowledge as soon as possible on GitHub.

1. Acknowledge and triage report
2. Reproduce issue and assess severity
3. Prepare patch and regression tests
4. Coordinate disclosure timeline
5. Publish patch notes and mitigation guidance

• Treat all PPTX files as untrusted input.
• Configure zipLimits in production; RECOMMENDED_ZIP_LIMITS is the package-provided starting point.
• Run rendering in constrained browser/container contexts when possible.
• Keep dependencies and runtime updated.
• Disable or limit external navigation integration if your application does not need it.
• Pin exact standalone and PDF.js asset versions; do not use mutable CDN URLs in production.
• If EMF-PDF fallback is enabled, permit only the required module origin and blob: in worker-src; self-host the assets when a tighter CSP is required.

RECOMMENDED_ZIP_LIMITS protects the ZIP parsing stage:

• maxEntries: 4000
• maxEntryUncompressedBytes: 32 MiB
• maxTotalUncompressedBytes: 256 MiB
• maxMediaBytes: 192 MiB
• maxConcurrency: 8

These limits are checked from ZIP metadata when available and from the actual decoded entry size when metadata is unavailable. The decoded-size fallback covers XML/text entries as well as media entries, which prevents oversized entries from bypassing limits through missing JSZip private size metadata.

Embedded font loading applies safe defaults without requiring configuration:

• At most 16 faces are loaded per presentation.
• EOT input is limited to 8 MiB per face.
• Decoded font data is limited to 16 MiB per face and 32 MiB per presentation.
• A 250 ms soft batch deadline stops additional synchronous decode work from starting.

Trusted applications can use embeddedFontLimits to provide finite, non-negative partial overrides; omitted fields keep the defaults exported as DEFAULT_EMBEDDED_FONT_LIMITS. Malformed, oversized, slow, or unloadable faces are skipped so text falls back to host fonts. Because the MTX decoder is synchronous, the time deadline cannot interrupt a face already in progress and may be exceeded by that final face.

The renderer also applies semantic limits after ZIP parsing:

• Chart data caches cap point indexes at 10,000 and ignore oversized c:ptCount allocation hints.
• EMF bitmap previews are rejected when decoded pixels exceed 16,777,216, dimensions exceed 8192x8192, or the declared pixel payload is incomplete.
• External audio/video URLs require TargetMode="External" and safe http/https protocols; media elements are created with preload="none" to avoid automatic fetches during render.
• CSS length, tile-position, and SVG path parsing use bounded linear scanners rather than backtracking expressions on attacker-controlled PPTX values.
• EMF-PDF fallback uses one short-lived isolated Worker per render. The Worker is terminated on success, error, cancellation, or after a 15-second timeout. At most four PDF fallback Workers run concurrently; additional work waits in an abortable queue.
• Disposing a slide aborts pending PDF fallback work and prevents late results from mutating detached DOM or repopulating a shared blob URL cache.