---
id: CVE-2026-42507
aliases:
  - GO-2026-5039
  - BIT-golang-2026-42507
title: Arbitrary inputs are included in errors without any escaping in net/textproto
summary: Arbitrary inputs are included in errors without any escaping in net/textproto
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'
vendor: stdlib
product: stdlib
ecosystem: go
affected:
  - 'stdlib >= 1.26.0-0, < 1.26.4'
patched:
  - stdlib 1.26.4
published: '2026-06-02'
updated: '2026-10-03'
sourceUpdated: '2026-10-03T10:41:52.575378248Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GO-2026-5039'
references:
  - url: 'https://go.dev/issue/79346'
  - url: 'https://go.dev/cl/777060'
  - url: 'https://groups.google.com/g/golang-announce/c/tKs3rmcBcKw'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42507.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-42507'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2484205'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-42507'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-42507'
  - url: 'https://pkg.go.dev/vuln/GO-2026-5039'
  - url: 'https://access.redhat.com/errata/RHSA-2026:49702'
  - url: 'https://access.redhat.com/errata/RHSA-2026:29980'
  - url: 'https://access.redhat.com/errata/RHSA-2026:38995'
  - url: 'https://access.redhat.com/errata/RHSA-2026:61253'
  - url: 'https://access.redhat.com/errata/RHSA-2026:57649'
  - url: 'https://access.redhat.com/errata/RHSA-2026:49712'
  - url: 'https://access.redhat.com/errata/RHSA-2026:66364'
  - url: 'https://access.redhat.com/errata/RHSA-2026:29981'
  - url: 'https://access.redhat.com/errata/RHSA-2026:23262'
  - url: 'https://access.redhat.com/errata/RHSA-2026:23264'
  - url: 'https://access.redhat.com/errata/RHSA-2026:50205'
  - url: 'https://access.redhat.com/errata/RHSA-2026:33612'
  - url: 'https://access.redhat.com/errata/RHSA-2026:57194'
  - url: 'https://access.redhat.com/errata/RHSA-2026:59556'
tags:
  - osv
  - go
  - csaf
  - vex
  - red-hat
epss: 0.0037
epssPercentile: 0.30793
cvssSource: vendor
cwe:
  - CWE-117
ingestedAt: '2026-07-31T19:10:07.997Z'
---

## Overview

When returning errors, functions in the net/textproto package would include its input as part of the error. This might allow an attacker to inject misleading content to errors that are printed or logged.

## Affected packages

- `stdlib >= 1.26.0-0, < 1.26.4`

## Remediation

Upgrade to a patched release:

- `stdlib 1.26.4`

## Vendor advisories

- **RHSA-2026:49702** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0) · released 2026-08-03 · [advisory](https://access.redhat.com/errata/RHSA-2026:49702)
- **RHSA-2026:29980** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-06-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:29980)
- **RHSA-2026:38995** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8) · released 2026-07-13 · [advisory](https://access.redhat.com/errata/RHSA-2026:38995)
- **RHSA-2026:61253** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.2) · released 2026-08-31 · [advisory](https://access.redhat.com/errata/RHSA-2026:61253)
- **RHSA-2026:57649** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.4) · released 2026-08-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:57649)
- **RHSA-2026:49712** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v.9.6) · released 2026-08-03 · [advisory](https://access.redhat.com/errata/RHSA-2026:49712)
- **RHSA-2026:66364** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9) · released 2026-09-10 · [advisory](https://access.redhat.com/errata/RHSA-2026:66364)
- **RHSA-2026:29981** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9) · released 2026-06-25 · [advisory](https://access.redhat.com/errata/RHSA-2026:29981)
- **RHSA-2026:23262** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-06-04 · [advisory](https://access.redhat.com/errata/RHSA-2026:23262)
- **RHSA-2026:23264** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-06-04 · [advisory](https://access.redhat.com/errata/RHSA-2026:23264)
- **RHSA-2026:50205** · Red Hat · fixed in: Red Hat OpenShift distributed tracing 3.10.2 · released 2026-08-04 · [advisory](https://access.redhat.com/errata/RHSA-2026:50205)
- **Red Hat VEX** · Moderate · affected: Assisted Installer for Red Hat OpenShift Container Platform 2, Builds for Red Hat OpenShift, cert-manager Operator for Red Hat OpenShift, Compliance Operator, Confidential Compute Attestation, Cryostat 4, … · no fix planned: Assisted Installer for Red Hat OpenShift Container Platform 2, Builds for Red Hat OpenShift, cert-manager Operator for Red Hat OpenShift, Compliance Operator, … · updated 2026-10-02 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42507.json)
- **RHSA-2026:33612** · Red Hat · fixed in: Red Hat OpenShift distributed tracing 3.10.2 · released 2026-06-30 · [advisory](https://access.redhat.com/errata/RHSA-2026:33612)