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

Should you act?

Normal patch cycle

No exploitation signal; fix it in your next routine update if you are affected. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• 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.

From the GitHub advisory

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.

pyminizip uses version 1.2.11 of zlib's code.

Weakness type: CWE-190.

Product: pyminizip (PyPI) · Assigned by: mitre · Published: 2023-10-14

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: required (a user must click/open something)
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• 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.

Timeline

• 2023-10-14 — CVE record published by mitre
• 2023-10-14 — GitHub-reviewed advisory GHSA-mq29-j5xf-cjwr published (critical)
• 2026-10-14 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. GLSA-202401-18 security.gentoo.org

Vulnerability records

1. GitHub Advisory GHSA-mq29-j5xf-cjwr github.com
2. CVE.org record CVE-2023-45853 cve.org
3. NVD entry CVE-2023-45853 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. winimage.com winimage.com
3. github.com github.com
4. chromium.googlesource.com chromium.googlesource.com
5. chromium.googlesource.com chromium.googlesource.com
6. [oss-security] 20231020 CVE-2023-45853: overflows in MiniZip in zlib through 1.3 openwall.com
7. [debian-lts-announce] 20231127 [SECURITY] [DLA 3670-1] minizip security update lists.debian.org
8. security.netapp.com security.netapp.com
9. pypi.org pypi.org
10. [oss-security] 20240124 Re: CVE-2023-45853: overflows in MiniZip in zlib through 1.3 openwall.com
11. cert-portal.siemens.com cert-portal.siemens.com
12. cert-portal.siemens.com cert-portal.siemens.com
13. cert-portal.siemens.com cert-portal.siemens.com
14. github.com github.com
15. github.com github.com

Critical PyPI advisories · Today’s Security Digest