Render failure via empty Files.Lines input
Published Jul 17, 2026 · Updated Jul 17, 2026
Improper array-index validation in Helm through 4.2.3 allows attackers to interrupt chart rendering with an empty chart file. Files.Lines treats a non-nil zero-length file slice as valid, converts it to an empty string, then reads s[len(s)-1] and panics. A chart must invoke Files.Lines on the empty file; the recovered panic terminates template, install, upgrade, lint, or SDK rendering with a nonzero error.
Summary
What happened
Improper array-index validation in Helm through 4.2.3 allows attackers to interrupt chart rendering with an empty chart file. Files.Lines treats a non-nil zero-length file slice as valid, converts it to an empty string, then reads s[len(s)-1] and panics. A chart must invoke Files.Lines on the empty file; the recovered panic terminates template, install, upgrade, lint, or SDK rendering with a nonzero error.
The record
- CVE
- CVE-2026-63308
- Published
- Jul 17, 2026
- Updated
- Jul 17, 2026
- Vendor
- The Helm Project
- Product
- Helm
- Classifications
- CWE-129, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 17, 2026CVE publishedPublication date reported by the CVE source.
- Jul 17, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <=4.2.3
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Helm Files.Lines empty-file proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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