CVE-2026-42507 Arbitrary inputs are included in errors without any escaping in net/textproto
Attackers can inject misleading content into error logs via unescaped inputs in the Go net/textproto package, potentially confusing log analysis.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42507?
CVE-2026-42507 is a medium-severity vulnerability in Go standard library net/textproto, published on 2 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-42507?
2 open source packages ship an affected version, including golang and stdlib.
| Package | Affected | Fixed in |
|---|---|---|
golang Bitnami | All versions | 1.25.11, 1.26.4 |
stdlib Go | All versions | 1.25.11, 1.26.4 |
Linux distribution packages (2)
golang Rocky Linux:10 | All versions | 0:1.26.4-1.el10_2 |
golang Rocky Linux:9 | All versions | 0:1.26.4-1.el9_8 |
How do I fix CVE-2026-42507?
Upgrade golang to a fixed version for your release line: 1.25.11 or 1.26.4.
Is CVE-2026-42507 being exploited?
There is no known exploitation of CVE-2026-42507 in the wild and no public exploit code.
Sources
Also known as AZL-89363, AZL-89369, AZL-98808, BELL-CVE-2026-42507, BIT-golang-2026-42507, CLEANSTART-2026-BB23669 and 983 more.