# CVE-2026-63499: zt-zip: ZipUtil.unpack can change file permissions of output directory

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

zt-zip is a Java library that provides convenience methods for ZIP archive manipulation. Prior to 1.18.1, ZipUtil.unpack(...) can apply stored ZIP-entry permissions to the extraction output directory when an entry name such as / or ./ resolves to that directory itself. Because the path traversal checks permit self-referencing entries that do not escape the destination, the unpacker's permission-handling path can replace restrictive output-directory permissions with attacker-supplied permissions. This affects applications that unpack untrusted ZIP files, and POSIX systems demonstrate the issue directly, while ZTFilePermissionsUtil.fetchDefaultStrategy provides fallback permission handling on other supported systems. This issue is fixed in version 1.18.1.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- zeroturnaround / zt-zip: < 1.18.1 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 4.0: 6.9 (medium); CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-23

## Exploit evidence

- exploit: https://github.com/zeroturnaround/zt-zip/security/advisories/GHSA-v2g6-7r9j-v6px (ADP: CISA-ADP)

## References

- https://github.com/zeroturnaround/zt-zip/security/advisories/GHSA-v2g6-7r9j-v6px (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/zeroturnaround/zt-zip/pull/191 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/zeroturnaround/zt-zip/commit/1b625467b4c3cd3a9bee9efc35bdef2f8d9c8dad (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/zeroturnaround/zt-zip/releases/tag/v1.18.1 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/zeroturnaround/zt-zip/security/advisories/GHSA-v2g6-7r9j-v6px (ADP: CISA-ADP; exploit)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-63499; retrieved 2026-11-03; source updated 2026-11-03

Revision: 2e7d0f7d224a7bbd69becec79bc8273917ed7e96952753b6c193123e477a4bc4

Canonical: https://y2.dev/cve/CVE-2026-63499

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.