Package substitution via unsigned Hex API metadata
Published Jul 29, 2026 · Updated Jul 29, 2026
Insufficient data-authenticity verification in Gleam 0.18.0 through 1.17.0 allows man-in-the-middle attackers to substitute Hex packages. The dependency resolver writes the unsigned Hex API response's outer_checksum into manifest.toml, then accepts a forged tarball matching that value instead of trusted signed metadata. Exploitation requires fresh dependency resolution and control of both responses through TLS trusted by the process; an unchanged known-good manifest remains pinned.
Summary
What happened
Insufficient data-authenticity verification in Gleam 0.18.0 through 1.17.0 allows man-in-the-middle attackers to substitute Hex packages. The dependency resolver writes the unsigned Hex API response's outer_checksum into manifest.toml, then accepts a forged tarball matching that value instead of trusted signed metadata. Exploitation requires fresh dependency resolution and control of both responses through TLS trusted by the process; an unchanged known-good manifest remains pinned.
The record
- CVE
- CVE-2026-59247
- Published
- Jul 29, 2026
- Updated
- Jul 29, 2026
- Vendor
- Gleam
- Product
- Gleam
- Classifications
- CWE-345, T1195.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 29, 2026CVE publishedPublication date reported by the CVE source.
- Jul 29, 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=0.18.0 <1.18.0
- Affected versionversion=8447b78cc844ff4aec44eea23dbd68d1fea11f11 <c9c0d48c123c8abae6db8dd61b25ccb427ed3d35
- Affected versionversion=v0.18.0-elixir-alpine <v1.18.0-elixir-alpine
- Affected versionversion=v0.18.0-elixir-slim <v1.18.0-elixir-slim
- Affected versionversion=v0.18.0-elixir <v1.18.0-elixir
- Affected versionversion=v0.18.0-erlang-alpine <v1.18.0-erlang-alpine
- Affected versionversion=v0.18.0-erlang-slim <v1.18.0-erlang-slim
- Affected versionversion=v0.18.0-erlang <v1.18.0-erlang
- Affected versionversion=v0.18.0-node-alpine <v1.18.0-node-alpine
- Affected versionversion=v0.18.0-node-slim <v1.18.0-node-slim
- Affected versionversion=v0.18.0-node <v1.18.0-node
- Affected versionversion=v1.6.0-scratch <v1.18.0-scratch
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
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
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Technologies
Your stack
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Your stack
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