Medium severity · published Mar 30, 2026
CVE-2026-33983
FreeRDP: Progressive Codec Quant BYTE Underflow - UB + CPU DoS
6.5
CVSS
0.4%
EPSS
No
On KEV
Description
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.24.2, progressive_decompress_tile_upgrade() detects a mismatch via progressive_rfx_quant_cmp_equal() but only emits WLog_WARN, execution continues. The wrapped value (247) is used as a shift exponent, causing undefined behavior and an approximately 80 billion iteration loop (CPU DoS). This issue has been patched in version 3.24.2.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 38% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FR
FreeRDP · FreeRDP
< 3.24.2 · source: vendor, NVD
RH
Red Hat Enterprise Linux 10 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 10.0 Extended Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 6 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 7 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.2 Advanced Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.6 Telecommunications Update Service · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33983
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-33983
Patch
https://github.com/FreeRDP/FreeRDP/commit/78188ab479c8e6eb9ba2475b3732c76b4bbe5425
Patch
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-4gfm-4p52-h478
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:10709
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:11332
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:11333
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:11336
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