CVE-2026-76845: Adm zip Adm-zip Extraction Follows Destination Symlinks, Vulnerability

MODERATE
Advisory Identifier: GHSA-vwc7-r8mq-g2x9
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CVSS 6.5
CWE-59
Published
Advisory Summary

CVE-2026-76845 is a MODERATE (CVSS 6.5) adm-zip extraction follows destination symlinks, vulnerability (CWE-59: Improper Link Resolution Before File Access ('Link Following')) affecting Adm zip libraries in the npm ecosystem. The issue involves adm-zip extraction follows destination symlinks, allowing arbitrary file overwrite. Remediation is available in the latest vendor maintenance releases.

CVE-2026-76845 at a Glance

CVE Identifier CVE-2026-76845
GHSA Identifier GHSA-vwc7-r8mq-g2x9
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-59: Improper Link Resolution Before File Access ('Link Following')
Affected Product Adm zip
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N).

Attack Vector Local (AV:L)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Changed (S:C)
Confidentiality None (C:N)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2026-76845

To remediate this vulnerability, upgrade all affected Adm zip dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

adm-zip fixed: Latest secure release 
npm install adm-zip@Latest secure release
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls adm-zip

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-76845, inspect your project dependencies using npm:

npm ls adm-zip

Analyze the terminal output to locate any version of Adm zip in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The npm ls adm-zip command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-59: Improper Link Resolution Before File Access ('Link Following'), where the product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource. In Adm zip, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2026-76845 Affected Adm zip Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
adm-zip
npm/adm-zip
npm
≥ 0.5.9
≤ 0.6.0

References

NVD — CVE-2026-76845 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-76845
Adm zip Source Repository REPOSITORY
https://github.com/cthackers/adm-zip/issues/574
Adm zip Source Repository REPOSITORY
https://github.com/cthackers/adm-zip/pull/575
Adm zip Source Repository REPOSITORY
https://github.com/cthackers/adm-zip
Adm zip Source Repository REPOSITORY
https://github.com/cthackers/adm-zip/blob/v0.6.0/util/utils.js
www.vulncheck.com/advisories/adm-zip-... WEB
https://www.vulncheck.com/advisories/adm-zip-through-arbitrary-file-overwrite-via-symlink-following-on-extraction

Frequently Asked Questions

What is CVE-2026-76845?
CVE-2026-76845 is a security vulnerability in Adm zip involving adm-zip extraction follows destination symlinks, allowing arbitrary file overwrite under CWE-59: Improper Link Resolution Before File Access ('Link Following').
Which Adm zip versions are affected?
Affected versions include releases prior to current release patches across affected packages: adm-zip.
What version fixes CVE-2026-76845?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is adm-zip affected?
Yes, adm-zip is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2026-76845?
CVE-2026-76845 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N.
What CWE is associated with CVE-2026-76845?
CVE-2026-76845 is classified under CWE-59: Improper Link Resolution Before File Access ('Link Following') (The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.).
How can I check npm dependencies for CVE-2026-76845?
Run the dependency tree command: 'npm ls adm-zip'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-vwc7-r8mq-g2x9",
  "modified" : "2026-09-08T21:20:41Z",
  "published" : "2026-08-24T15:31:51Z",
  "aliases" : [ "CVE-2026-76845" ],
  "summary" : "adm-zip extraction follows destination symlinks, allowing arbitrary file overwrite",
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "adm-zip"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.5.9"
      }, {
        "last_affected" : "0.6.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-76845"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/cthackers/adm-zip/issues/574"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/cthackers/adm-zip/pull/575"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/cthackers/adm-zip"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/cthackers/adm-zip/blob/v0.6.0/util/utils.js"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/adm-zip-through-arbitrary-file-overwrite-via-symlink-following-on-extraction"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-59" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-08T21:20:41Z",
    "nvd_published_at" : "2026-08-24T14:17:02Z"
  }
}