CVE-2026-42507Network attack vector

Log forgery via unescaped protocol error input

Published Jun 2, 2026 · Updated Jun 2, 2026

Log injection in Go net/textproto before 1.25.11 and 1.26.0-0 through 1.26.3 allows remote attackers to forge output via protocol input. The parsing routines concatenate malformed response lines and MIME headers into ProtocolError values, while Error.Error formats Msg without quoting or escaping. Exploitation requires an application to process attacker-controlled protocol data and then print or log the resulting error, enabling forged lines or terminal control sequences without reported code execution or service interruption.

CVSS severity5.3
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Log injection in Go net/textproto before 1.25.11 and 1.26.0-0 through 1.26.3 allows remote attackers to forge output via protocol input. The parsing routines concatenate malformed response lines and MIME headers into ProtocolError values, while Error.Error formats Msg without quoting or escaping. Exploitation requires an application to process attacker-controlled protocol data and then print or log the resulting error, enabling forged lines or terminal control sequences without reported code execution or service interruption.

The record

CVE
CVE-2026-42507
Published
Jun 2, 2026
Updated
Jun 2, 2026
Vendor
The Go Project
Product
net/textproto
Classifications
CWE-532, T1565.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 2, 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 <1.25.11
  2. Affected versionversion=1.26.0-0 <1.26.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Go Project · net/textprotoversion=0 <1.25.11; version=1.26.0-0 <1.26.4

Published CVSS scores

5.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-532Insertion of Sensitive Information into Log File
T1565.001Stored Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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