What’s Vulnerable › Vulnerabilities

CVE-2026-33983: FreeRDP: Progressive Codec Quant BYTE Underflow - UB + CPU DoS

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-30 · updated 2026-07-15
• Weakness: CWE-190

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.

Affected products

• FreeRDP: before 3.24.2 — fixed in 3.24.2

How to fix

Upgrade to a fixed version: FreeRDP 3.24.2. Check the vendor advisory for mitigations.

References

• https://github.com/FreeRDP/FreeRDP/commit/78188ab479c8e6eb9ba2475b3732c76b4bbe5425
• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-4gfm-4p52-h478
• https://access.redhat.com/errata/RHSA-2026:10709
• https://access.redhat.com/errata/RHSA-2026:11332
• https://access.redhat.com/errata/RHSA-2026:11333
• https://access.redhat.com/errata/RHSA-2026:11336
• https://access.redhat.com/errata/RHSA-2026:11649
• https://access.redhat.com/errata/RHSA-2026:11651
• https://access.redhat.com/errata/RHSA-2026:12359
• https://access.redhat.com/errata/RHSA-2026:12388
• https://access.redhat.com/errata/RHSA-2026:19033
• https://access.redhat.com/errata/RHSA-2026:19349

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