CVE-2026-117556

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

• ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.32% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 25.8% of scored records. A rank, not a probability.

NVD base score

5.3 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

NVD analysis status

Deferred. NVD last modified this record on 2026-10-28.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2026-10-27 13:07Z1 DAY AGO

Last updated

2026-10-28 16:17Z17 HR AGO

Reserved

2026-10-27

Assigning CNA

VulnCheck

Record state

PUBLISHED

Severity

Medium (CVSS 5.3)

CNA CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Weaknesses

• CWE-125Out-of-bounds ReadBase

Data version

5.2

Document digest

a5846b6731e1e3196980eed534060db5b6713c64efba07ad96ad814b123a14f5

• github.comGitHub Issue #119https://github.com/zchunk/zchunk/issues/119issue-tracking
• github.comhttps://github.com/zchunk/zchunkproduct
• github.comhttps://github.com/zchunk/zchunk/commit/02b371a64bf98245df97315d07c684a0ca5ea1dfpatch
• github.comzchunk 1.5.5 Release Noteshttps://github.com/zchunk/zchunk/releases/tag/1.5.5release-notes
• github.comhttps://github.com/zchunk/zchunk/blob/1.5.4/src/lib/header.c#L167technical-description
• www.vulncheck.comVulnCheck Advisory: zchunk before 1.5.5 Heap Out-of-Bounds Read via read_preface()https://www.vulncheck.com/advisories/zchunk-before-1.5.5-heap-out-of-bounds-read-via-read-prefacethird-party-advisory