Out-of-bounds Write Affecting zlib package, versions <1:1.3.dfsg+really1.3.1-1+e2


Severity

Recommended
0.0
high
0
10

Snyk's Security Team recommends NVD's CVSS assessment. Learn more

Threat Intelligence

EPSS
0.36% (28th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-ECHOLATEST-ZLIB-19529341
  • published4 Sept 2026
  • disclosed3 Sept 2026

Introduced: 3 Sep 2026

CVE-2026-85091  (opens in a new tab)
CWE-787  (opens in a new tab)

How to fix?

Upgrade Echo:latest zlib to version 1:1.3.dfsg+really1.3.1-1+e2 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream zlib package and not the zlib package as distributed by Echo. See How to fix? for Echo:latest relevant fixed versions and status.

zlib versions 1.3.1.2 through 1.3.2 contain a heap buffer overflow vulnerability in the gz_vacate() function when processing non-blocking gzwrite() operations with stale external buffer pointers. Attackers can trigger the overflow by calling gzprintf() or gzvprintf() after a write stall, causing an unchecked memmove() to write beyond the internal input buffer boundary.

CVSS Base Scores

version 3.1