CVE-2026-42501Network attack vector

Remote code execution via empty checksum responses

Published May 7, 2026 · Updated May 7, 2026

Checksum validation bypass in Go command before 1.25.10 and 1.26.0-0 through 1.26.2 allows remote attackers to execute altered toolchains. The command accepts a successful checksum-database response with no matching module entry, treating an empty or unrelated signed response as validation. Exploitation requires an untrusted module proxy or checksum database and a module or toolchain download, after which attacker-supplied code runs with the invoking user's privileges.

CVSS severity7.5
High
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Checksum validation bypass in Go command before 1.25.10 and 1.26.0-0 through 1.26.2 allows remote attackers to execute altered toolchains. The command accepts a successful checksum-database response with no matching module entry, treating an empty or unrelated signed response as validation. Exploitation requires an untrusted module proxy or checksum database and a module or toolchain download, after which attacker-supplied code runs with the invoking user's privileges.

The record

CVE
CVE-2026-42501
Published
May 7, 2026
Updated
May 7, 2026
Vendor
Go
Product
Go command
Classifications
CWE-347, T1195.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 7, 2026CVE publishedPublication date reported by the CVE source.
  2. May 7, 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.

  1. Affected versionversion=0 <1.25.10
  2. Affected versionversion=1.26.0-0 <1.26.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Go · Go commandversion=0 <1.25.10; version=1.26.0-0 <1.26.3

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1195.002Compromise Software Supply Chain

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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