Secuno
ENNL
Book demo

CVE-2026-55191

Freerdp buffer overflow

9.8 CRITICALPublic exploitEPSS 0.83%
  1. Published19 Aug 2026

Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, FreeRDP clients that negotiate RDPGFX AVC444 with an H.264 decoder backend calculate the intermediate YUV444 allocation size in libfreerdp/codec/h264.c with 32-bit multiplication in avc444_ensure_buffer. A malicious RDP server can supply surface dimensions for which piDstStride multiplied by padDstHeight wraps to a small nonzero value, causing winpr_aligned_recalloc to allocate an undersized buffer before YUV420CombineToYUV444 writes using the actual stride and rectangle dimensions. This can cause a client crash and may permit code execution through attacker-influenced heap corruption. This issue is fixed in version 3.27.0.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Freerdp< 3.27.0

Remediation

Fixed in
Freerdp≥ 3.27.0

References

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

CVE-2026-195698.8
dynamic_object_create() in kernel/userspace/userspace.c computed the backing allocation…
CVE-2026-148888.1
IBM DataPower Gateway 10.5.0.0 through 10.5.0.22, 10.6.1 through 10.6.6, 10.6.0.0…
CVE-2026-142699.8
IBM DataPower Gateway 10.5.0.0 through 10.5.0.22, 10.6.1 through 10.6.6, 10.6.0.0…
CVE-2026-764719.8
A vulnerability in the NX-API feature of Cisco NX-OS Software could allow an…
CVE-2026-465708.1
In NTFS-3G before 2026.7.7, a heap buffer overflow exists in ntfs_index_walk_down() in…
CVE-2026-593469.3
VMware Workstation and Fusion contain an integer-overflow vulnerability. A malicious…

Frequently asked

Is CVE-2026-55191 being actively exploited?

CVE-2026-55191 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.83%.

How severe is CVE-2026-55191?

CVE-2026-55191 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.83% probability of exploitation.

Which products are affected by CVE-2026-55191?

Affected products include Freerdp.

How do I fix CVE-2026-55191?

Upgrade affected software to a fixed version, for example Freerdp 3.27.0 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-55191 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

See how prioritisation worksBook a demo

Get Patch this first every Monday

Five vulnerabilities that matter this week, ranked on real exploitation. Plain language, one email, no spam.

You can unsubscribe with one click from every issue. We handle your details as described in our privacy policy.

Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.