CVE-2026-31806 | FreeRDP has a Heap Buffer Overflow in nsc_process_message() via Unchecked SURFACE_BITS_COMMAND Bitmap Dimensions

Exp

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.24.0, the gdi_surface_bits() function processes SURFACE_BITS_COMMAND messages sent by the RDP server. When the command is handled using NSCodec, the bmp.width and bmp.height values provided by the server are not properly validated against the actual desktop dimensions. A malicious RDP server can supply crafted bmp.width and bmp.height values that exceed the expected surface size. Because these values are used during bitmap decoding and memory operations without proper bounds checking, this can lead to a heap buffer overflow. Since the attacker can also control the associated pixel data transmitted by the server, the overflow may be exploitable to overwrite adjacent heap memory. 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-2026-31806 is rated Exploit Available (54/100): CVSS Critical severity, with low exploitation likelihood (EPSS 0.02%). 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-2026-31806

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

Exploit prediction scoring system (EPSS) score for CVE-2026-31806

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 2026-03-21 0.06% 0.02% -0.04%
2 2026-03-19 0.04% 0.06% +0.01%
3 2026-03-14 — 0.04% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-31806

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.3 4.0 CRITICAL
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:H)
High confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:H)
High integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:H)
High availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.
Exploit maturity (threat) (E:X)
Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:X)
Not evaluated.
Recovery (supplemental) (R:X)
Not evaluated.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:X)
Not evaluated.
Provider urgency (supplemental) (U:X)
Not evaluated.
 — — [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-2026-31806

OS Trackers for CVE-2026-31806

vendor priority summary link
alpine — CVE-2026-31806: 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-2026-31806
debian not yet assigned CVE-2026-31806 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-2026-31806
redhat high — https://access.redhat.com/security/cve/CVE-2026-31806
suse high CVE-2026-31806 severity important: SUSE including 59 source package names (freerdp-2.11.2-150600.4.18.1, freerdp-2.11.7-1.el9_7.5, …), 63 product×package rows across 8 product lines (SUSE Liberty Linux 8, SUSE Liberty Linux 9, … (8 product lines)): Fixed 63. https://www.suse.com/security/cve/CVE-2026-31806/
ubuntu medium CVE-2026-31806 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-2026-31806

Affected software / configurations for CVE-2026-31806

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

References for CVE-2026-31806

cvelogic Threat Intelligence