Answer in brief
CVE-2026-85091 records a High severity (CVSS 7.4) vulnerability in zlib 1.3.1.2 through 1.3.2 Heap Buffer Overflow via gz_vacate. The current sources do not mark it as known exploited. The current feed maps zlib/zlib (generic), zlib/zlib (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps zlib/zlib (generic), zlib/zlib (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| zlib/zlibgeneric | 1.3.1.2 | Not reported |
| zlib/zlibgeneric | >=1.3.1.2 <=1.3.2 | Not reported |
Published upstream
Sep 3, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 9, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 3, 2026
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.
Quoted source text, attributed separately from HOL analysis.