Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| zchunk | zchunk | < 1.5.5 | 1.5.5 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | zchunk | No fix yet | — |
| Debian 13 | zchunk | No fix yet | — |
| Debian 12 | zchunk | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | zchunk | No fix yet | — |
| Ubuntu 26.04 LTS | zchunk | No fix yet | — |
| Ubuntu 24.04 LTS | zchunk | No fix yet | — |
| Ubuntu 22.04 LTS | zchunk | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Hardened Images 1 | zchunk +2 | 1.5.5-1.hum1 | RHSA-2026:90996 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | zchunk | 1.5.1-150700.3.3.1 | SUSE-SU-2026:5138-1 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | zchunk | 1.5.1-160000.3.1 | SUSE-SU-2026:24657-1 |
| SLES 16.0 | zchunk | 1.5.1-160000.3.1 | SUSE-SU-2026:24657-1 |
| SLE Micro 6.2 | zchunk | 1.5.1-160000.3.1 | SUSE-SU-2026:24640-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | zchunk | 1.5.1-160000.3.1 | openSUSE-SU-2026:22250-1 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | zchunk | 1.5.5-1 | — |
Advisories 5
- RHSA-2026:90996 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- SUSE-SU-2026:24657-1 Security update for zchunk SUSE / openSUSE Security Updates · Nov 12, 2026
- SUSE-SU-2026:24640-1 Security update for zchunk SUSE / openSUSE Security Updates · Nov 12, 2026
- openSUSE-SU-2026:22250-1 Security update for zchunk SUSE / openSUSE Security Updates · Nov 11, 2026
- SUSE-SU-2026:5138-1 Security update for zchunk SUSE / openSUSE Security Updates · Nov 10, 2026
References
- GitHub Issue #119 issue-tracking
- https://github.com/zchunk/zchunk product
- https://github.com/zchunk/zchunk/commit/02b371a64bf98245df97315d07c684a0ca5ea1df patch
- zchunk 1.5.5 Release Notes release-notes
- https://github.com/zchunk/zchunk/blob/1.5.4/src/lib/header.c#L167 technical-description
- VulnCheck Advisory: zchunk before 1.5.5 Heap Out-of-Bounds Read via read_preface() third-party-advisory