Threat Intelligence Database

wasm2c in WebAssembly wabt through 1.0.41 allows sandbox escape in some situations that primarily involve 32-bit platforms, aka a "table flip" attack. It does not check the return value of calloc() in wasm_rt_allocate_funcref_table() (wasm2c/wasm-rt-impl-tableops.inc). When the funcref table allocation fails, table->data is left NULL while table->size keeps the guest-declared element count; thus, bounds checks still pass and table element accesses resolve to absolute memory addresses (i * sizeof(wasm_rt_funcref_t)). This gives arbitrary read and write of host process memory and - via table.get, table.set, and call_indirect - arbitrary code execution, defeating the isolation that wasm2c exists to provide (a full sandbox escape). wasm2c is used as an in-process sandboxing boundary by RLBox and WasmBoxC, including in Firefox, which compiles the Graphite, Hunspell, Ogg, Expat, and Woff2 libraries via wasm2c to contain untrusted font, media, and XML input. Therefore, sandboxing in these applications is potentially affected. Exploitation requires the funcref table allocation to fail, for example under an address-space limit (RLIMIT_AS), on 32-bit hosts, with vm.overcommit_memory=2, or under memory pressure. On 64-bit Linux with default overcommit the allocation succeeds and the defect is not triggered. The wasm2c memory allocator aborts on calloc failure in the same runtime; the table allocator lacks this abort behavior. This was introduced in commit ab9e0b55 (PR #813).

A security vulnerability has been detected in WebAssembly wabt up to 1.0.39. This issue affects the function wabt::Decompiler::VarName of the file /src/repro/wabt/bin/wasm-decompile of the component wasm-decompile. Such manipulation leads to out-of-bounds read. Local access is required to approach this attack. The exploit has been disclosed publicly and may be used. Unfortunately, the project has no active maintainer at the moment. In a reply to the issue report somebody recommended to the researcher to provide a PR himself.

MediumVulnerabilityUnited StatesGermanyChina+7#cve#cve-2025-15412

A weakness has been identified in WebAssembly wabt up to 1.0.39. This vulnerability affects the function wabt::AST::InsertNode of the file /src/repro/wabt/bin/wasm-decompile of the component wasm-decompile. This manipulation causes memory corruption. It is possible to launch the attack on the local host. The exploit has been made available to the public and could be used for attacks. Unfortunately, the project has no active maintainer at the moment. In a reply to the issue report somebody recommended to the researcher to provide a PR himself.

MediumVulnerabilityUnited StatesGermanyJapan+7#cve#cve-2025-15411