# openSUSE-SU-2026:20851-1: Security update for putty

> PuTTY contains a double-free and crash in RSA/ECDSA handling, allowing remote attackers to cause denial of service or potentially execute code.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 31 May 2026

## What is openSUSE-SU-2026:20851-1?

openSUSE-SU-2026:20851-1 is a memory corruption vulnerability, published on 31 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

This update for putty fixes the following issues:

Changes in putty:

- Update to release 0.84
  * Fixed a remotely triggerable double-free in RSA key exchange.
  * Fixed a remotely triggerable crash (assertion failure - program
    termination) in NIST ECDSA signature verification.
  * Fixed marking of Telnet and Rlogin session data with a trust
    sigil after you authenticated to a proxy (possibly allowing a
    server to spoof a repeat proxy password prompt).
  * New ability to run a specified command before starting the
    connection, e.g. to perform wake-on-LAN or a port knock.
  * Display 'pre-edit text', showing the progress of using multiple
    keystrokes to compose a single Unicode character.
  * Improved support for to running the GUI tools on Wayland (fixed
    startup issues and tuned performance).
  * Configuring a SSH certificate authority used to fail unless you
    manually made a config directory, now fixed.
  * Fixed a spurious "Network error: Socket is not connected" when
    authenticating to some HTTP proxies.

## Which versions are affected by openSUSE-SU-2026:20851-1?


## How do I fix openSUSE-SU-2026:20851-1?

No fix has been published for openSUSE-SU-2026:20851-1 yet. Limit exposure of the affected software until one is available.

## Is openSUSE-SU-2026:20851-1 being exploited?

There is no known exploitation of openSUSE-SU-2026:20851-1 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for openSUSE-SU-2026:20851-1 and fix it if it is affected.

What it is: openSUSE-SU-2026:20851-1 is a memory corruption vulnerability, published on 31 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of openSUSE-SU-2026:20851-1 in the wild and no public exploit code.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/openSUSE-SU-2026-20851-1/ (Markdown: https://insights.sbomify.com/openSUSE-SU-2026-20851-1/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/openSUSE-SU-2026:20851-1

---
From sbomify Insights: https://insights.sbomify.com/openSUSE-SU-2026-20851-1/
Summaries are generated and may contain mistakes; the official description above is the record.