zt-zip: ZipUtil.unpack can change file permissions of output directory
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- Proof of concept public, per CISA
- Fix
- Fixed in 1.18.1
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 1.18.1.
- Exploitation15/40CISA rates a proof of concept as public
- Exposure?/25Exposure: unknown (data gap). No advisory context yet
- Reach?/20Reach: unknown (data gap). No tracked technology or package matched
- Severity6.9/10CVSS 6.9
- No patch0/5No signal
What would change the score
- Would score about 62 if added to CISA KEV
- Would score about 57 if CISA's SSVC rates exploitation active
- Would score about 44 if advisories confirm default setups are exposed
CVE-2026-63499 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 6.9 (medium) and affects zt-zip; fixed in 1.18.1.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 22/100 · provisional
- Fix
- Fixed in 1.18.1
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: poc
- Automatable: no
- Technical impact: partial
Summary
The zt-zip Java library, which provides ZIP archive handling utilities, is affected when its unpack method is used on untrusted ZIP files. An attacker-crafted archive can overwrite the permissions of the extraction directory with attacker-chosen permissions, most directly on POSIX systems.
Read the original description
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.
What to do
Upgrade to a fixed version: 1.18.1.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: poc · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- zeroturnaround zt-zip
fixed in 1.18.1
Evidence 4
- Advisory
- Repository
- Repository
- Repository
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-63499
Is CVE-2026-63499 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. CISA's SSVC assessment notes a proof of concept exists. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-63499?
zt-zip: before 1.18.1.Source: cve.now feed data
How do I fix CVE-2026-63499?
Upgrade to a fixed version: 1.18.1.Source: cve.now feed data