PT-2026-23418 · Zlib · Zlib

Calysteon · CVE-2026-27820 · Published 2026-03-05 · Updated 2026-07-16

Positive Technologies (AI Summary)

CVSS v2.0

10

Critical

Base vector

AV:N/AC:L/Au:N/C:C/I:C/A:C

Name of the Vulnerable Software and Affected Versions Zlib versions prior to the patched version.

Description A buffer overflow issue exists in the Zlib::GzipReader component. The vulnerability could potentially allow for unexpected behavior.

Recommendations Update to the patched version to resolve this issue.

Exploit

Fix

Buffer Overflow

Weakness Enumeration

CWE-131

CWE-120

Related Identifiers

BDU:2026-06116

CVE-2026-27820

ECHO-CDF4-0E18-2536

GHSA-G857-HHFV-J68W

RHSA-2026:7305

RHSA-2026:7307

RHSA-2026:8838

SUSE-SU-2026:1066-1

USN-8556-1

Affected Products

Zlib

References · 39

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27820.json · Exploit
• 🔥 https://github.com/rubysec/ruby-advisory-db/blob/master/gems/zlib/CVE-2026-27820.yml · Exploit
• https://github.com/ruby/zlib/security/advisories/GHSA-g857-hhfv-j68w · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-42258 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-27820 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-g857-hhfv-j68w · Vendor Advisory
• https://osv.dev/vulnerability/BELL-CVE-2026-27820 · Vendor Advisory
• https://osv.dev/vulnerability/USN-8556-1 · Vendor Advisory
• https://osv.dev/vulnerability/ALPINE-CVE-2026-27820 · Vendor Advisory
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-27820 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2026-27820 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2026-27820 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-27820 · Security Note
• https://ubuntu.com/security/CVE-2026-27820 · Vendor Advisory
• https://ubuntu.com/security/notices/USN-8556-1 · Vendor Advisory