Aszx87410

pnpm allows a transitive dependency alias within registry package metadata to include path traversal segments. During the installation process, pnpm utilizes this alias as a filesystem path when linking dependency nodes. This allows a registry package to cause `pnpm install --ignore-scripts` to replace project paths with symlinks pointing to dependency package directories controlled by an attacker.

In non-frozen mode, `pnpm install` may accept new remote package content even after detecting that the downloaded tarball does not match the integrity recorded in `pnpm-lock.yaml`. If a registry serves different metadata and tarball content for a package name and version already locked with an integrity value, pnpm reports an integrity mismatch but then performs a resolution repair. This process accepts the new integrity from the registry, updates the lockfile, installs the new content, and exits successfully, meaning the lockfile integrity check does not act as a hard stop by default. This behavior can be exploited if a registry is compromised or if a registry mirror/proxy serves mutated package content. In such cases, a new environment (such as a new machine or a new team member onboarding) may install a malicious replacement package despite the presence of a lockfile with the original integrity.

A denial of service issue exists due to regular expression backtracking in the Content-Disposition filename parameter parser. A crafted multipart upload containing a long header value can cause regex matching to take several seconds, which blocks the event loop. This affects any service that accepts multipart uploads using this library.