Arbitrary inputs are included in errors without any escaping in net/textproto (CVE-2026-42507) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-42507

Arbitrary inputs are included in errors without any escaping in net/textproto

Answer in brief

CVE-2026-42507 records a Unknown severity vulnerability in Arbitrary inputs are included in errors without any escaping in net/textproto. The current sources do not mark it as known exploited. The current feed maps stdlib (go). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jun 2, 2026Updated Aug 26, 2026Source checked Aug 26, 2026First seen by HOL Aug 26, 2026Material review Aug 26, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps stdlib (go). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
stdlibgo	>=0 <1.25.11 >=1.26.0-0 <1.26.4	1.25.11, 1.26.4

Recommended response

Check inventory. Check lockfiles and deployed manifests for stdlib.
Review the reported fix. Update stdlib to 1.25.11 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Jun 2, 2026
Evidence: source:osv:source_dates:source-dates:record
Source modified
Aug 26, 2026
Evidence: source:osv:source_dates:source-dates:record
First seen by HOL
Aug 26, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.