# CVE-2026-48850: Use after free in PuTTY

> A double free vulnerability in PuTTY's RSA key exchange allows attackers to potentially execute arbitrary code or cause a denial of service.

- **Severity:** Low 3.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 May 2026
- **Updated:** 26 May 2026
- **Also known as:** DEBIAN-CVE-2026-48850, GHSA-c27j-mcjp-93gg, UBUNTU-CVE-2026-48850

## What is CVE-2026-48850?

CVE-2026-48850 is a low-severity use after free vulnerability in PuTTY, published on 25 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

PuTTY 0.72 before 0.84 has a double free in RSA KEX.

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2026-48850?

It affects 1 product.


Products: Putty Putty.

## How do I fix CVE-2026-48850?

Upgrade to a fixed version.

## Is CVE-2026-48850 being exploited?

There is no known exploitation of CVE-2026-48850 in the wild and no public exploit code.

## Other vulnerabilities in PuTTY

- [CVE-2004-1008](https://insights.sbomify.com/CVE-2004-1008/): Integer overflow in n/a (critical 10.0)
- [CVE-2019-17067](https://insights.sbomify.com/CVE-2019-17067/): Other in n/a (critical 9.8)
- [CVE-2021-36367](https://insights.sbomify.com/CVE-2021-36367/): Auth bypass in n/a (high 8.1)
- [CVE-2016-6167](https://insights.sbomify.com/CVE-2016-6167/): Other in n/a (high 7.8)
- [CVE-2021-33500](https://insights.sbomify.com/CVE-2021-33500/): Denial of service in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-48850 and fix it if it is affected.

What it is: CVE-2026-48850 is a low-severity use after free vulnerability in PuTTY, published on 25 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 CVE-2026-48850 in the wild and no public exploit code.

Affected product: PuTTY. No package-level version data is available, so check the vendor advisory linked from the reference page.

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/CVE-2026-48850/ (Markdown: https://insights.sbomify.com/CVE-2026-48850/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-48850
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-48850
- OSV: https://osv.dev/vulnerability/CVE-2026-48850

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-48850/
Summaries are generated and may contain mistakes; the official description above is the record.