Answer in brief
CVE-2026-117556 records a Medium severity (CVSS 5.3) vulnerability in zchunk before 1.5.5 Heap Out-of-Bounds Read via read_preface(). The current sources do not mark it as known exploited. The current feed maps zchunk/zchunk (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 5.3. 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 zchunk/zchunk (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| zchunk/zchunkgeneric | >=0 <1.5.5 | 1.5.5 |
Published upstream
Oct 27, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 27, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 27, 2026
zchunk before 1.5.5 contains a heap out-of-bounds read vulnerability in read_preface() in src/lib/header.c that passes the total header length instead of remaining bytes to compint parsing functions. Attackers can supply a crafted .zck file whose header ends inside a compressed integer, causing reads past the heap header buffer and crashing the application.
Quoted source text, attributed separately from HOL analysis.