Wabt

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).

Published: 2026-09-12T23:16:34.123Z
Updated: 2026-10-23T19:16:43.958Z

A vulnerability was found in WebAssembly wabt up to 1.0.37. It has been declared as problematic. Affected by this vulnerability is the function GetFuncOffset of the file src/interp/binary-reader-interp.cc. The manipulation leads to use after free. It is possible to launch the attack on the local host. The exploit has been disclosed to the public and may be used. A similar issue reported during the same timeframe was disputed by the code maintainer because it might not affect "real world wasm programs". Therefore, this entry might get disputed as well in the future.

Published: 2025-06-19T19:31:06.618Z
Updated: 2025-06-23T19:30:26.829Z

A vulnerability was found in WebAssembly wabt up to 1.0.37. It has been classified as problematic. Affected is the function OnDataCount of the file src/interp/binary-reader-interp.cc. The manipulation leads to resource consumption. Attacking locally is a requirement. The exploit has been disclosed to the public and may be used. A similar issue reported during the same timeframe was disputed by the code maintainer because it might not affect "real world wasm programs". Therefore, this entry might get disputed as well in the future.

Published: 2025-06-19T19:00:16.150Z
Updated: 2025-06-23T19:30:32.208Z

A vulnerability was found in WebAssembly wabt up to 1.0.37 and classified as problematic. This issue affects the function LogOpcode of the file src/binary-reader-objdump.cc. The manipulation leads to reachable assertion. Local access is required to approach this attack. The exploit has been disclosed to the public and may be used. The real existence of this vulnerability is still doubted at the moment. The code maintainer explains that this issue might not affect "real world wasm programs".

Published: 2025-06-19T18:31:06.692Z
Updated: 2025-06-23T19:30:37.748Z

A vulnerability classified as problematic was found in WebAssembly wabt 1.0.36. Affected by this vulnerability is the function BinaryReaderInterp::BeginFunctionBody of the file src/interp/binary-reader-interp.cc. The manipulation leads to null pointer dereference. The attack can be launched remotely. The complexity of an attack is rather high. The exploitation appears to be difficult. The exploit has been disclosed to the public and may be used.

Published: 2025-04-02T22:00:14.705Z
Updated: 2025-04-03T19:18:20.492Z