CVE-2026-31883 | FreeRDP has a `size_t` underflow in ADPCM decoder leads to heap-buffer-overflow write

Exp

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.24.0, a size_t underflow in the IMA-ADPCM and MS-ADPCM audio decoders leads to heap-buffer-overflow write via the RDPSND audio channel. In libfreerdp/codec/dsp.c, the IMA-ADPCM and MS-ADPCM decoders subtract block header sizes from a size_t variable without checking for underflow. When nBlockAlign (received from the server) is set such that size % block_size == 0 triggers the header parsing at a point where size is smaller than the header (4 or 8 bytes), the subtraction wraps size to ~SIZE_MAX. The while (size > 0) loop then continues for an astronomical number of iterations. This vulnerability is fixed in 3.24.0.

Published: 2026-03-13 Last update: 2026-03-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-31883 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.07%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

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

Public exploit references (Exploit-DB) for CVE-2026-31883

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-31883

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 2026-04-24 0.03% 0.07% +0.04%
2 2026-03-14 — 0.03% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-31883

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:N/S:U/C:L/I:L/A:N 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:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 2.5 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]

Weakness enumeration for CVE-2026-31883

OS Trackers for CVE-2026-31883

vendor priority summary link
alpine — CVE-2026-31883: 1 source package rows (freerdp); 30 state rows across 2 repos (3.23-community, edge-community); fixed 2, open 28. https://security.alpinelinux.org/vuln/CVE-2026-31883
debian not yet assigned CVE-2026-31883 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-2026-31883
redhat medium — https://access.redhat.com/security/cve/CVE-2026-31883
suse high CVE-2026-31883 severity important: SUSE including 49 source package names (freerdp-2.11.2-150600.4.18.1, freerdp-3.10.3-150700.3.9.1, …), 53 product×package rows across 6 product lines (SUSE Linux Enterprise Module for Package Hub 15 SP7, SUSE Linux Enterprise Server 12 SP5-LTSS, … (6 product lines)): Fixed 53. https://www.suse.com/security/cve/CVE-2026-31883/
ubuntu medium CVE-2026-31883 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-2026-31883

Affected software / configurations for CVE-2026-31883

Vendor Product Version Raw CPE
freerdp freerdp < 3.24.0 cpe:2.3:a:freerdp:freerdp:*:*:*:*:*:*:*:*

References for CVE-2026-31883

cvelogic Threat Intelligence