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

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.

Published: 2026-03-30 Last update: 2026-04-01 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-33983 is rated Low Risk (31.7/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.05%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-33983

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-01 0.04% 0.05% +0.01%
2 2026-03-31 — 0.04% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-33983

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 3.6 [email protected]

Weakness enumeration for CVE-2026-33983

OS Trackers for CVE-2026-33983

vendor priority summary link
alpine — CVE-2026-33983: 1 source package rows (freerdp); 33 state rows across 2 repos (3.23-community, edge-community); fixed 2, open 31. https://security.alpinelinux.org/vuln/CVE-2026-33983
debian not yet assigned CVE-2026-33983 not yet assigned priority: Debian including 2 source packages (freerdp2, freerdp3), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 3, open 2. https://security-tracker.debian.org/tracker/CVE-2026-33983
redhat high — https://access.redhat.com/security/cve/CVE-2026-33983
suse medium — https://www.suse.com/security/cve/CVE-2026-33983/
ubuntu medium CVE-2026-33983 medium priority: Ubuntu including 3 source packages (freerdp, freerdp2, freerdp3), 16 status rows across 7 suites (bionic, focal, jammy, noble, questing, upstream, xenial): needs-triage 10, DNE 5, released 1. https://ubuntu.com/security/CVE-2026-33983

Affected software / configurations for CVE-2026-33983

Vendor Product Version Raw CPE
freerdp freerdp < 3.24.2 cpe:2.3:a:freerdp:freerdp:*:*:*:*:*:*:*:*

References for CVE-2026-33983

cvelogic Threat Intelligence