CVE-2026-48851 Security feature bypass in PuTTY
PuTTY fails to clear trust status between proxy authentication and main session, allowing bypass of visual trust indicators for TELNET data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-48851?
CVE-2026-48851 is a low-severity vulnerability in PuTTY, published on 25 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
PuTTY 0.77 before 0.84 uses a copy of the PuTTY icon as a trust indication for TELNET data but the trust status is not cleared between proxy authentication and the main session.
Weakness: CWE-451
Which versions are affected by CVE-2026-48851?
It affects 1 product.
Products include Putty Putty.
How do I fix CVE-2026-48851?
Upgrade to a fixed version.
Is CVE-2026-48851 being exploited?
There is no known exploitation of CVE-2026-48851 in the wild and no public exploit code.
Other vulnerabilities in PuTTY
Sources
Also known as DEBIAN-CVE-2026-48851, GHSA-5fwp-h8j4-xmhm, UBUNTU-CVE-2026-48851.