Invoking "go bug" follows symlinks in predictable temporary filenames in cmd/go (CVE-2026-39819) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-39819

Invoking "go bug" follows symlinks in predictable temporary filenames in cmd/go

Answer in brief

CVE-2026-39819 records a Unknown severity vulnerability in Invoking "go bug" follows symlinks in predictable temporary filenames in cmd/go. The current sources do not mark it as known exploited. The current feed maps toolchain (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 May 7, 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 toolchain (go). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
toolchaingo	>=0 <1.25.10 >=1.26.0-0 <1.26.3	1.25.10, 1.26.3

Recommended response

Check inventory. Check lockfiles and deployed manifests for toolchain.
Review the reported fix. Update toolchain to 1.25.10 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
May 7, 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

The "go bug" command writes to two files with predictable names in the system temporary directory (for example, "/tmp"). An attacker with access to the temporary directory can create a symlink in one of these names, causing "go bug" to overwrite the target of the symlink.

Quoted source text, attributed separately from HOL analysis.