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Fencer Vulns
medium 4.3

CVE-2026-63308 json

Helm Files.Lines Denial of Service via Empty Chart Files

published 2026-07-17 3 mo ago modified 2026-11-08 19 h ago also BIT-helm-2026-63308 , EUVD-2026-45213

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

Helm through 4.2.3, fixed in commit ba6c9a2, contains a denial of service vulnerability in the Files.Lines template helper in pkg/engine/files.go that allows attackers to trigger an index out of range panic by including zero-length byte slices in chart files. Attackers can include empty files in Helm charts to cause deterministic render failures across template, install, upgrade, lint, and SDK Engine.Render operations.

Patch / fix

  • bitnami helm 4.2.4
  • helm3 hummingbird 1 3.21.4-0.1.hum1
  • helm3 hummingbird 1 3.21.3-0.1.2.hum1
  • helm4 hummingbird 1 4.2.3-0.1.2.hum1

red hat advisories RHSA-2026:55180RHSA-2026:42241RHSA-2026:42230

  • helm SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 3.21.3-160000.2.1
  • helm Linux Micro 6.1 3.21.3-slfo.1.1_2.1
  • helm Linux Micro 6.0 3.21.3-2.1
  • c-ares Linux Micro 6.2 1.34.8-160000.1.1
  • helm SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +10 more 3.21.3-150000.1.93.1

suse advisories SUSE-SU-2026:23506-1SUSE-SU-2026:23688-1SUSE-SU-2026:23522-1SUSE-SU-2026:23456-1SUSE-SU-2026:3882-1

  • helm openSUSE Leap 16.0 3.21.3-160000.2.1
  • helm openSUSE Tumbleweed 4.2.3-4.1
  • helm3 openSUSE Tumbleweed 3.21.3-4.1

opensuse advisories openSUSE-SU-2026:21809-1openSUSE-SU-2026:11386-1openSUSE-SU-2026:11387-1

  • cert-manager Azure Linux 3.0 1.12.15-11

azure linux advisories AZL-92991

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-63308 updated cvss 4.3

Helm: Helm: Denial of Service via malformed chart files

  • Red Hat OpenShift Developer Tools and Services helm Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/multicluster-operators-subscription-rhel9 Red Hat OpenShift GitOps openshift-gitops-1/argocd-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images helm3 3.21.4-0.1.hum1, helm4 4.2.3-0.1.2.hum1, helm3 3.21.3-0.1.2.hum1
    fixed: vendor fix RHSA-2026:42241

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/helm/helm/issues/32279 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 5.3 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
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
CNA 4.0 5.3 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 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
bitnami helm
<4.2.4
4.2.4

Affected products

  • helm helm

Classification

Weakness
  • CWE-129 Improper Validation of Array Index

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.