CVE-2026-63308: Helm Files.Lines Denial of Service via Empty Chart Files
Vulnerability summary
CVE-2026-63308 is a medium (CVSS 6.5) Improper Validation of Array Index vulnerability in helm. EPSS estimates a 0.49% chance of exploitation in the next 30 days, higher than 41.9% of scored vulnerabilities. 1 public exploit is recorded.
Not severe (CVSS 5.3, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 8 · Related 7Timeline
- 17-07-2026PublishedVulnerability first disclosed.
- 29-10-2026Last modifiedVulnerability information updated.
Description
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.
CVSS metrics
7 scores · 5 sources · 2 versions- OSV · WolfiEcosystem advisory · calculated5.3MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- OSV · ChainguardEcosystem advisory · calculated5.3MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- NVDNIST5.3MediumCVSS: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
- CVE.orgCNA4.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:LDiffers
- OSV · Red hatEcosystem advisory · calculated4.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:LDiffers
EPSS trend
Probability
0.49%
Chance of exploitation in the next 30 days
Percentile
42%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.49% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
1 foundHelm
Maturity: poc
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, no authentication, user interaction (CVSS vector). Other conditions: not stated in public data.
Chainguard2 products
- helm-3All versions (No fix recorded)
- helm-4< 4.2.4-r0
Opensuse2 products
- helm3&distro=openSUSE Tumbleweed< 3.21.3-4.1
- helm&distro=openSUSE Tumbleweed< 4.2.3-4.1
Wolfi2 products
- helm-3All versions (No fix recorded)
- helm-4< 4.2.4-r0
Helm1 product
- helm≤ 4.2.3
Redhat1 product
- helm3< 0:3.21.4-0.1.hum1
5 vendors · 8 products
References
16 links- images.redhat.comARTICLE
Show all 16 references
- github.com/helm/helmPACKAGE