Executive brief
NanaZip is an open-source file archiver for Windows. A vulnerability in its WebAssembly file handler allows a specially crafted, small file to trigger massive memory allocations when the file is opened or extracted. This can lead to the application crashing or the system running out of memory, potentially causing a denial of service for the user.
Technical details
A vulnerability exists in NanaZip's WebAssembly archive handler (NanaZip.Codecs.Archive.WebAssembly.cpp) due to improper validation of ULEB128 length fields. Specifically, the 'NameSize' and 'Information.Size' fields are used to allocate std::string and std::vector buffers without being checked against the actual file size or remaining stream bytes. An attacker can provide a tiny .wasm file with a declared name length of 0xFFFFFFFF, forcing a ~4 GiB allocation during the archive listing (Open) or extraction phase. This results in a denial of service via memory exhaustion (std::bad_alloc). The issue is fixed in version 6.5.1749.0 by implementing bounds checking against the remaining bundle size.
Affected products
- M2Team NanaZip < 6.5.1749.0
Timeline
- 2026-06-16: advisory: GitHub Security Advisory published
- 2026-06-16: patched: Fixed in version 6.5.1749.0
- 2026-07-10: disclosed: NVD publication date
References
- https://github.com/M2Team/NanaZip/commit/1ce90f2d14a984476d0407a835273705607facf2
- https://github.com/M2Team/NanaZip/commit/56aee89037947410dd5e66f3a087e0f290484bae
- https://github.com/M2Team/NanaZip/commit/92b12a6e1eb0cf8e88fcc277aa7508ca1ff27db6
- https://github.com/M2Team/NanaZip/releases/tag/6.5.1749.0
- https://github.com/M2Team/NanaZip/security/advisories/GHSA-qxhc-2v6p-wm8m