High [CVE-2026-113679] Out-of-bounds write via crafted font in WebAssembly shaper
This high-severity Red Hat Linux advisory covers CVE-2026-113679; related products: Red Hat Hardened Images.
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Summary
Out-of-bounds write via crafted font in WebAssembly shaper. Red Hat rates this moderate (CVSS 7).
Weakness: CWE-787.
Affected product named by the advisory: Red Hat Hardened Images.
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 hours ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 13 hours ago·verify at source
Mitigation checklist
- --- CME Mitigation Guidance (2026-10-20) --- Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure. The highest-value action is to disable or compile out the experimental WebAssembly shaper in HarfBuzz builds to prevent executing font-embedded Wasm modules: upgrade to the fixed Harfbuzz builds, which update the native symbol signature to use integers, treat the buffer argument as a guest offset, and validate the full memory range using HB_ARRAY_PARAM before writing, closing all 2 injection vectors (crafted font file containing an embedded WebAssembly module, out-of-bounds guest offset call to font_glyph_to_string). Until patched, this is only a concern on applications and hosts running HarfBuzz compiled with the experimental WebAssembly shaper enabled (-Dwasm=enabled) — HarfBuzz installations built without the experimental WebAssembly shaper enabled are unaffected — so prevent target applications from loading untrusted or third-party font files and restrict user rendering of untrusted documents containing embedded fonts. As a compensating measure, enable Address Space Layout Randomization to randomize host process memory layout and hinder address targeting, compile host binaries with full RELRO and PIE to protect global offset table entries from being overwritten, enforce Control Flow Integrity and shadow call stacks to block unauthorized control-flow transfers if return addresses or pointers are corrupted, and enable Arbitrary Code Guard on Windows platforms to prevent allocating or converting writable memory into executable pages. These controls limit blast radius and contain exploitation, but they do not fix the underlying incorrect function signature defect — apply the upstream patch to fully remediate. Highest-impact CME: CME-1309 Script Engine Restriction (Sandbox / Disable) (high)
Official advisory · high-confidence parse· fetched 13 hours ago·verify at source
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