CVE-2026-39819

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.

CVSS v3.1 Score

5.3

MEDIUM

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.01%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-59 CWE-59

Affected Products

Vendor	Product	Versions
golang	go	< 1.25.10
golang	go	1.26.0 — 1.26.3

References

Advisories & Patches

https://go.dev/cl/763882 https://pkg.go.dev/vuln/GO-2026-4978

Other References

https://go.dev/issue/78584 https://groups.google.com/g/golang-announce/c/qcCIEXso47M

Frequently Asked Questions

What is CVE-2026-39819? +

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. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-39819? +

CVE-2026-39819 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-39819? +

CVE-2026-39819 affects products from golang, specifically: go. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-39819? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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