# CVE-2026-16517: libarchive signed integer overflow in ZIP writer

Source: https://junglewise.ai/threats/cve-2026-16517-libarchive-signed-integer-overflow-in-zip-writer  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-21. Updated: 2026-07-22  
License: CC BY 4.0 with a link back

CVE-2026-16517 · Severity: low · CVSS 2.9 · Published 2026-07-21

libarchive is a widely used library for reading and writing various archive formats like ZIP and TAR. A flaw in its ZIP writing component could cause the software to behave unpredictably or crash when processing extremely large encrypted files. Because this requires creating a file of nearly 9 quintillion bytes, the practical risk to most business operations is very low.

Technologies: [Red Hat Enterprise Linux 10](https://junglewise.ai/threats/technologies/enterprise-linux-10), [Red Hat Enterprise Linux 6](https://junglewise.ai/threats/technologies/enterprise-linux-6), [Red Hat Enterprise Linux 7](https://junglewise.ai/threats/technologies/enterprise-linux-7), [Red Hat Enterprise Linux 8](https://junglewise.ai/threats/technologies/enterprise-linux-8), [Red Hat Enterprise Linux 9](https://junglewise.ai/threats/technologies/enterprise-linux-9), [Red Hat OpenShift Container Platform 4](https://junglewise.ai/threats/technologies/openshift-container-platform-4). Vendors: [Red Hat](https://junglewise.ai/threats/vendors/red-hat).

## Quick answers

**Is CVE-2026-16517 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-16517 being exploited in the wild.

**How severe is CVE-2026-16517?** Low severity, with a CVSS score of 2.9, published 21 July 2026.

**Which products and versions are affected?** Red Hat Enterprise Linux 10 affected; Red Hat Enterprise Linux 6 affected; Red Hat Enterprise Linux 7 affected; Red Hat Enterprise Linux 8 affected; and 2 more.

**Is there a fix for CVE-2026-16517?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-16517 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-16517?** Check whether you run Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7 or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A signed integer overflow vulnerability exists in libarchive's ZIP writer within the `archive_write_zip_header` function in `archive_write_set_format_zip.c`. The flaw is triggered when ZIP encryption (such as AES-256) is enabled and a file entry size is near `INT64_MAX`. Adding the encryption overhead to the uncompressed entry size causes an overflow of the `int64_t` variable, leading to undefined behavior. This can result in incorrect Zip64 extension logic or potential memory corruption. Exploitation is considered unlikely as it requires the write path to handle a file size approaching the theoretical limit of a 64-bit signed integer. An upstream fix has been identified in pull request 3228.

## Affected products

- libarchive libarchive unspecified
- Red Hat Red Hat Enterprise Linux 6 affected
- Red Hat Red Hat Enterprise Linux 7 affected
- Red Hat Red Hat Enterprise Linux 8 affected
- Red Hat Red Hat Enterprise Linux 9 affected
- Red Hat Red Hat Enterprise Linux 10 affected
- Red Hat Red Hat OpenShift Container Platform 4 affected

## Timeline

- 2026-07-21: disclosed: Vulnerability reported and CVE assigned.
- 2026-07-21: advisory: Red Hat published security advisory.

## References

- [https://access.redhat.com/downloads/content/package-browser/](https://access.redhat.com/downloads/content/package-browser/)
- [https://access.redhat.com/security/cve/CVE-2026-16517](https://access.redhat.com/security/cve/CVE-2026-16517)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2505492](https://bugzilla.redhat.com/show_bug.cgi?id=2505492)

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