---
title: "CVE-2023-45853: pyminizip affected by zlib's integer overflow/heap based buffer overflow vulnerability due to vulnerable dependency"
url: https://erroneo.us/security/cve/CVE-2023-45853/
description: "CVE-2023-45853 (pyminizip (PyPI)): MiniZip in zlib through 1.3 has an integer overflow and resultant heap-based buffer overflow in zipOpenNewFileInZip464…"
type: vulnerability-record
section: "Security Digest"
date_published: 2023-10-14
date_modified: 2026-10-14
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2023-45853"
kev: false
cvss: 8.8
epss: 0.03448
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2023-45853: pyminizip affected by zlib's integer overflow/heap based buffer overflow vulnerability due to vulnerable dependency

**Signal:** Normal patch cycle. No exploitation signal; fix it in your next routine update if you are affected. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 3.4% , percentile 89: FIRST’s model estimates a 3.4% chance of exploitation activity in the next 30 days, higher than 89% of all scored CVEs (elevated). EPSS is a probability, not a verdict.
- Needs a user to click or open something. Phishing makes that realistic, but it is not wormable.
- Only applies if your dependency tree includes pyminizip (PyPI) <= 0.2.6, no fixed version listed . Check your lockfile, including transitive dependencies.

## What it is

MiniZip in zlib through 1.3 has an integer overflow and resultant heap-based buffer overflow in zipOpenNewFileInZip464 via a long filename, comment, or extra field. NOTE: MiniZip is not a supported part of the zlib product. NOTE: pyminizip through 0.2.6 is also vulnerable because it bundles an affected zlib version, and exposes the applicable MiniZip code through its compress API.

## Affected packages

- PyPI `pyminizip` <= 0.2.6 → fixed: none listed

## Affected products (CVE record)

- n/a n/a: see advisory

## Severity

- CISA-ADP CVSS 3.1: 8.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 3.45% probability of exploitation activity in the next 30 days; percentile 89.

## Sources

- [GLSA-202401-18](https://security.gentoo.org/glsa/202401-18)
- [GitHub Advisory GHSA-mq29-j5xf-cjwr](https://github.com/advisories/GHSA-mq29-j5xf-cjwr)
- [CVE.org record CVE-2023-45853](https://www.cve.org/CVERecord?id=CVE-2023-45853)
- [NVD entry CVE-2023-45853](https://nvd.nist.gov/vuln/detail/CVE-2023-45853)
- [github.com](https://github.com/madler/zlib/pull/843)
- [winimage.com](https://www.winimage.com/zLibDll/minizip.html)
- [github.com](https://github.com/madler/zlib/blob/ac8f12c97d1afd9bafa9c710f827d40a407d3266/contrib/README.contrib#L1-L4)
- [chromium.googlesource.com](https://chromium.googlesource.com/chromium/src/+/de29dd6c7151d3cd37cb4cf0036800ddfb1d8b61)
- [chromium.googlesource.com](https://chromium.googlesource.com/chromium/src/+/d709fb23806858847131027da95ef4c548813356)
- [[oss-security] 20231020 CVE-2023-45853: overflows in MiniZip in zlib through 1.3](http://www.openwall.com/lists/oss-security/2023/10/20/9)
- [[debian-lts-announce] 20231127 [SECURITY] [DLA 3670-1] minizip security update](https://lists.debian.org/debian-lts-announce/2023/11/msg00026.html)
- [security.netapp.com](https://security.netapp.com/advisory/ntap-20231130-0009/)
- [pypi.org](https://pypi.org/project/pyminizip/#history)
- [[oss-security] 20240124 Re: CVE-2023-45853: overflows in MiniZip in zlib through 1.3](http://www.openwall.com/lists/oss-security/2024/01/24/10)
- [cert-portal.siemens.com](https://cert-portal.siemens.com/productcert/html/ssa-398330.html)
- [cert-portal.siemens.com](https://cert-portal.siemens.com/productcert/html/ssa-769027.html)
- [cert-portal.siemens.com](https://cert-portal.siemens.com/productcert/html/ssa-470355.html)
- [github.com](https://github.com/madler/zlib/commit/73331a6a0481067628f065ffe87bb1d8f787d10c)
- [github.com](https://github.com/smihica/pyminizip/blob/master/zlib-1.2.11/contrib/minizip/zip.c)

---
Source page: https://erroneo.us/security/cve/CVE-2023-45853/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt