Is CVE-2026-121396 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-121396 being exploited in the wild.

How severe is CVE-2026-121396?

Medium severity, with a CVSS score of 4.3, published 3 November 2026.

How is CVE-2026-121396 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-121396?

Check whether you run FreeRDP at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-121396: FreeRDP reachable assertion in RTS padding validation

CVE-2026-121396 · Severity: medium · CVSS 4.3 · Published 2026-11-03

FreeRDP is a remote desktop protocol client used to connect to Windows servers and RD Gateways. When connecting through an attacker-controlled RD Gateway, a malformed RPC-over-HTTP packet can trigger an assertion error in debug builds, causing the client to crash and disconnecting the user. This is a denial-of-service attack affecting only clients configured to use a gateway.

Technologies: FreeRDP. Vendors: FreeRDP.

Quick answers

Is CVE-2026-121396 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-121396 being exploited in the wild.
How severe is CVE-2026-121396?: Medium severity, with a CVSS score of 4.3, published 3 November 2026.
Which products and versions are affected?: FreeRDP 3.0.0 to 3.32.1.
Is there a fix for CVE-2026-121396?: Yes: fixed in 3.32.2. Until then: Disable verbose WinPR assertions at build time by not setting WITH_VERBOSE_WINPR_ASSERT=ON, or only connect through trusted RD Gateways under your control. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-121396 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-121396?: Check whether you run FreeRDP at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: 3.32.2

Disable verbose WinPR assertions at build time by not setting WITH_VERBOSE_WINPR_ASSERT=ON, or only connect through trusted RD Gateways under your control.

Technical details

The vulnerability is a reachable assertion in the rts_read_auth_verifier function that validates RTS authentication padding. When processing a crafted RTS PDU with inconsistent authentication padding values, the WINPR_ASSERT macro aborts the process on builds compiled with WITH_VERBOSE_WINPR_ASSERT=ON. The attacker must control or intercept the RD Gateway connection; normal release builds with verbose assertions disabled reject the packet cleanly and do not crash.

Affected products

FreeRDP FreeRDP 3.0.0 to 3.32.1

Timeline

2026-10-19: disclosed: GitHub security advisory published
2026-11-03: advisory: CVE-2026-121396 assigned

References

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