CVE-2026-76845 adm-zip 0.5.9 through 0.6.0 Arbitrary File Overwrite via Symlink Following on Extraction
Attackers can overwrite arbitrary files outside the extraction directory by exploiting symlink following in adm-zip when overwrite is enabled.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-76845?
CVE-2026-76845 is a medium-severity path traversal vulnerability in cthackers adm-zip, published on 24 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
adm-zip 0.5.9 through 0.6.0 follows symbolic links at the extraction destination. Utils.sanitize in util/utils.js enforces containment by comparing only the string form of an archive entry name against the resolved extraction root, and Utils.writeFileTo opens the computed destination with fs.openSync(path, "w", 0o666), which resolves symbolic links and carries neither O_NOFOLLOW nor a pre-write fs.lstatSync check. When a path component at the destination already exists as a symbolic link pointing outside the extraction root, extractAllTo, extractAllToAsync and extractEntryTo write the entry contents through that link and then chmod its target, placing attacker-controlled content in a file outside the root without any traversal sequence appearing in the archive. Reaching the write requires overwrite to be enabled, because the preceding fs.existsSync check also resolves the link and otherwise declines. An attacker able to create a symbolic link inside a shared, reused or predictable extraction directory, such as a temporary directory or a continuous integration workspace, can overwrite any file the extracting process is permitted to write.
Weakness: CWE-59
Which versions are affected by CVE-2026-76845?
2 open source packages ship an affected version, including adm-zip.
| Package | Affected | Fixed in |
|---|---|---|
adm-zip npm | From 0.5.9 to 0.6.0 | None |
adm-zip npm | From 0.5.9 to 0.6.0 | None |
How do I fix CVE-2026-76845?
Upgrade to a fixed version.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-76845 being exploited?
There is no known exploitation of CVE-2026-76845 in the wild and no public exploit code.
Sources
Also known as CLEANSTART-2026-FG34886, CLEANSTART-2026-RO21037, CLSA-2026-1790457506, GHSA-vwc7-r8mq-g2x9, MINI-236m-6jh4-qq8m, MINI-2j5x-hg3c-22hj and 12 more.