CVE-2026-1858 wget2 Improper Certificate Validation

Medium 4.8 Published 29 Apr 2026 Updated 30 Apr 2026

Attackers can bypass TLS certificate validation in wget2 by reusing certificates with incorrect Key Usage extensions, enabling man-in-the-middle attacks.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-1858?

CVE-2026-1858 is a medium-severity vulnerability in gnu wget2, published on 29 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

wget2 accepts a server certificate with incorrect Key Usage (KU) or Extended Key Usage (EKU). If the attackers compromise a certificate (with the associated private key) issued for a different purpose, they may be able to reuse it for TLS server authentication.

Weakness: CWE-20

Which versions are affected by CVE-2026-1858?

It affects 1 product.

Products include Gnu Wget2.

How do I fix CVE-2026-1858?

No fix has been published for CVE-2026-1858 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-1858 being exploited?

There is no known exploitation of CVE-2026-1858 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2026-1858, GHSA-9h5h-4q77-cphm, UBUNTU-CVE-2026-1858.