PuTTY 0.72 before 0.84 has a double free in RSA KEX. (CVE-2026-48850)
Description
PuTTY versions 0.72 through 0.83-3build1 contain a double free vulnerability in the RSA key exchange (KEX) implementation. This flaw can cause a denial of service by crashing the application. The vulnerability has a medium severity rating with a CVSS score of 5.9. No information about available patches or vendor advisories is provided.
CVSS v3.1
Score 5.9medium
Affected software
pkg:deb/ubuntu/putty?arch=source&distro=xenialpkg:deb/ubuntu/putty?arch=source&distro=bionicpkg:deb/ubuntu/putty?arch=source&distro=focalpkg:deb/ubuntu/putty?arch=source&distro=jammypkg:deb/ubuntu/putty?arch=source&distro=noblepkg:deb/ubuntu/putty?arch=source&distro=questingpkg:deb/ubuntu/putty?arch=source&distro=stonkingpkg:deb/ubuntu/putty?arch=source&distro=resoluteRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
A double free vulnerability exists in the RSA key exchange code of PuTTY versions from 0.65-2 up to and including 0.83-3build1. This vulnerability can lead to application crashes, resulting in denial of service. The CVSS 3.1 base score is 5.9, reflecting network attack vector, high attack complexity, no privileges required, no user interaction, unchanged scope, no confidentiality or integrity impact, but high impact on availability.
Potential Impact
The vulnerability allows an unauthenticated attacker to cause a denial of service by triggering a double free in the RSA key exchange process, crashing the PuTTY client. There is no reported impact on confidentiality or integrity. No known exploits are reported in the wild.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is confirmed, avoid using affected versions or consider alternative secure SSH clients. Monitor official PuTTY channels for updates.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-48850
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:16.04:LTS","Ubuntu:18.04:LTS","Ubuntu:20.04:LTS","Ubuntu:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:25.10","Ubuntu:26.10","Ubuntu:26.04:LTS"]
- Cvss Version
- 3.1
Threat ID: 6ad3f61d2cdf04f6566641a0
Added to database: 10/17/2026, 22:26:37 UTC
Last enriched: 10/18/2026, 01:05:15 UTC
Last updated: 10/18/2026, 01:05:15 UTC
Views: 2
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