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Vulnerability Database · RubyGems · Package report

zlib: vulnerability history, versions and safety

zlib is a package in the RubyGems ecosystem. Vulert records 1 vulnerability for it across 3 releases, first recorded in Apr 2026. Each vulnerability names the versions it affects, the fixed version to move to, and a workaround where no fix has been published.

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1 vulnerabilities recorded M1
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0 with no fix published

Every vulnerability has a patched version to move to.

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1 in the last 12 months

Most recent disclosure 16 Apr 2026.

See the disclosure history →
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0 malicious-package vulnerabilities

No published version shipped hostile code.

See all zlib vulnerabilities

Vulert verdict on zlib 3.2.4 i

Updated on 23 Oct 2026

Good news: 3.2.4, the version you would install today, has no known vulnerabilities. Older releases do — the table below lists all 1.

Package health score 96/100
  • Security No known security issues
  • Maintenance Sustainable
  • Popularity Not enough data
  • Community Not enough data

What to do: Stay on 3.2.4 or newer. This can change: a vulnerability disclosed tomorrow can affect 3.2.4 too — Vulert watches the package and alerts you if that happens. Monitor it with Vulert →

  • Current release 3.2.4 — unaffected i
  • Vulnerabilities on record 1 over 1 year · 1 in the last year i
  • Latest disclosure 16 Apr 2026 i
  • Highest CVSS 5.9 i
  • With no published fix 0 i
  • Last release this month i
  • Licence Ruby i

Version list, release dates, licence and dependants published by RubyGems, refreshed 23 Oct 2026. Licence information is not legal advice.

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01 Versions

Which versions are affected

Every version Vulert tracks for zlib, newest first, with the vulnerabilities recorded against each one. A version showing none has no vulnerability in the Vulert database — open it for the full picture on that release.

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Version Released Vulert vulnerabilities Licence Fix published Details
3.2.4 08 Oct 2026 none Ruby — Details →
3.2.3 05 Mar 2026 none Ruby — Details →
3.1.2 05 Mar 2026 none Ruby — Details →
3.0.1 05 Mar 2026 none Ruby — Details →
3.2.2 29 Oct 2025 M1 Ruby Yes Details →
3.2.1 17 Dec 2024 M1 Ruby Yes Details →
3.2.0 12 Nov 2024 M1 Ruby Yes Details →
3.1.1 29 May 2024 none Ruby — Details →
3.1.0 07 Nov 2023 none Ruby — Details →
3.0.0 05 Dec 2022 none Ruby — Details →
2.1.1 19 Oct 2021 none Ruby — Details →
2.1.0 14 Oct 2021 none Ruby — Details →
2.0.0 14 Oct 2021 none Ruby — Details →
1.1.0 30 Nov 2019 none BSD-2-Clause — Details →
1.0.0 11 Dec 2017 none BSD-2-Clause — Details →
0.1.0 13 Sep 2017 none BSD-2-Clause — Details →
0.0.1 11 May 2017 none BSD-2-Clause — Details →

All 17 versions Vulert tracks for this package. Severity counts are the vulnerabilities recorded against that exact release.

02 Disclosure history

How often vulnerabilities are recorded

  • 2026 1

Counted by the year Vulert recorded each vulnerability — the same date the table below shows as disclosed. 1 of the 1 were recorded in the last 12 months.

03 Vulnerabilities

Recorded vulnerabilities for zlib

The 1 most severe of 1 vulnerabilities recorded for this package

Search all 1 in the database →
Vulnerability Severity Fixed version ↑ Disclosed ↑
CVE-2026-27820: Buffer Overflow in Zlib Package's GzipReader Leading to Memory Corruption 5.9 medium 3.2.3 16 Apr 2026

Vulnerability wrong, a fix missing, or a package we should cover? Report it and we will fix the record. Report Vulnerability Provide Feedback

Updated: 23/Oct/2026 · Vulnerabilities in our DB: 524315

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Questions

About zlib

Is zlib safe to use?

Vulert records 1 vulnerabilities for zlib in RubyGems: 0 critical, 0 high, 1 medium and 0 low. Every one of them has a published fix, so the practical answer is to run a supported release and keep it patched.

What is zlib's Vulert package health score?

Vulert scores zlib 96/100, which reads as healthy. The score weighs the vulnerability record (40), maintenance and release cadence (25), adoption from dependents and stars (20) and community signals such as the OpenSSF scorecard and forks (15).

Is the latest version of zlib affected?

No. 3.2.4, the version you would install today, has no vulnerabilities on record against it. Earlier releases do — the version table above lists each release with what affects it.

Which version of zlib should I use?

3.2.4 is the version Vulert recommends for the affected releases. The version table above lists every release with the vulnerabilities recorded against it, so you can confirm the range you actually run.

How many vulnerabilities does zlib have?

1 vulnerability is recorded for zlib in the RubyGems ecosystem: 0 critical, 0 high, 1 medium and 0 low. The ledger on this page lists the same counts next to the date of the most recent disclosure.

How often are new zlib vulnerabilities disclosed?

1 vulnerability was recorded for zlib in the last 12 months, and the oldest entry in this database dates to 16 Apr 2026. Recency matters more than a lifetime total: it shows how actively new issues are being disclosed for the package you are considering.

Which versions of zlib are affected?

Each vulnerability on this page lists the affected version range and the fixed version to move to. Open the vulnerability for the version you actually run — fixes are specific to a release line, not to the package as a whole.

How do I monitor zlib for upcoming vulnerabilities?

Upload the manifest or SBOM for your application at vulert.com/scanner and Vulert keeps checking the zlib version you actually run against new disclosures, then alerts you when one affects it. There is no installation and no source-code access required.