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NVD / CVE Program· CNA GitHub_M

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

CriticalCVSS 9.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 39/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.36% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: FreeRDP FreeRDP 3.24.0.
  • Severity is disputed: the assigning authority (CNA) scores it 6.5, NVD 9.8.

Low priority for now. Upgrade to FreeRDP FreeRDP 3.24.0 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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
Mar 13, 2026
Updated
Jun 17, 2026
EPSS
0.3% · 30th percentile

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
proof of concept
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
9.8
CNA · GitHub_M
6.5
3.3 point gap

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-31883

When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
freerdpfreerdp

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • FreeRDP FreeRDP

    • < 3.24.0affected

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • freerdp freerdpbefore 3.24.0

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10freerdpbefore 2:3.10.3-5.el10_1.82:3.10.3-5.el10_1.8
AlmaLinux:10freerdp-develbefore 2:3.10.3-5.el10_1.82:3.10.3-5.el10_1.8
AlmaLinux:10freerdp-libsbefore 2:3.10.3-5.el10_1.82:3.10.3-5.el10_1.8
AlmaLinux:10freerdp-serverbefore 2:3.10.3-5.el10_1.82:3.10.3-5.el10_1.8
AlmaLinux:10libwinprbefore 2:3.10.3-5.el10_1.82:3.10.3-5.el10_1.8
AlmaLinux:10libwinpr-develbefore 2:3.10.3-5.el10_1.82:3.10.3-5.el10_1.8
AlmaLinux:8freerdpbefore 2:2.11.7-9.el8_102:2.11.7-9.el8_10
AlmaLinux:8freerdp-develbefore 2:2.11.7-9.el8_102:2.11.7-9.el8_10
AlmaLinux:8freerdp-libsbefore 2:2.11.7-9.el8_102:2.11.7-9.el8_10
AlmaLinux:8libwinprbefore 2:2.11.7-9.el8_102:2.11.7-9.el8_10
AlmaLinux:8libwinpr-develbefore 2:2.11.7-9.el8_102:2.11.7-9.el8_10
AlmaLinux:9freerdpbefore 2:2.11.7-7.el9_8.32:2.11.7-7.el9_8.3
AlmaLinux:9freerdpbefore 2:2.11.7-1.el9_7.72:2.11.7-1.el9_7.7
AlmaLinux:9freerdp-develbefore 2:2.11.7-7.el9_8.32:2.11.7-7.el9_8.3
AlmaLinux:9freerdp-develbefore 2:2.11.7-1.el9_7.72:2.11.7-1.el9_7.7
AlmaLinux:9freerdp-libsbefore 2:2.11.7-1.el9_7.72:2.11.7-1.el9_7.7
AlmaLinux:9freerdp-libsbefore 2:2.11.7-7.el9_8.32:2.11.7-7.el9_8.3
AlmaLinux:9libwinprbefore 2:2.11.7-7.el9_8.32:2.11.7-7.el9_8.3
AlmaLinux:9libwinprbefore 2:2.11.7-1.el9_7.72:2.11.7-1.el9_7.7
AlmaLinux:9libwinpr-develbefore 2:2.11.7-7.el9_8.32:2.11.7-7.el9_8.3
AlmaLinux:9libwinpr-develbefore 2:2.11.7-1.el9_7.72:2.11.7-1.el9_7.7
Alpine:v3.23freerdpbefore 3.24.0-r03.24.0-r0
Debian:12freerdp2from 0—
Debian:13freerdp3before 3.15.0+dfsg-2.1+deb13u23.15.0+dfsg-2.1+deb13u2

+96

Same product

freerdp: all records

Other highest-scoring records for the same primary product.

  • CVE-2018-8787FreeRDP prior to version 2.0.0-rc4 contains an Integer Overflow that leads to a Heap-Based Buffer Overflow in function…
    42Plan
  • CVE-2018-8788FreeRDP prior to version 2.0.0-rc4 contains an Out-Of-Bounds Write of up to 4 bytes in function nsc_rle_decode() that results in a memory…
    41Plan
  • CVE-2018-8786FreeRDP prior to version 2.0.0-rc4 contains an Integer Truncation that leads to a Heap-Based Buffer Overflow in function…
    41Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-29776Mar 13, 2026 · FreeRDP has an Integer Underflow in update_read_cache_bitmap_order Function of FreeRDP's Core Library
    12Monitor
  • ← EarlierCVE-2026-31806Mar 13, 2026 · FreeRDP has a Heap Buffer Overflow in nsc_process_message() via Unchecked SURFACE_BITS_COMMAND Bitmap Dimensions
    37Monitor
  • Later →CVE-2026-31884Mar 13, 2026 · FreeRDP has a division-by-zero in ADPCM decoders when `nBlockAlign` is 0
    30Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
FreeRDP FreeRDP3.24.0 · descriptionVendor (CNA)
almalinux:freerdp2:3.10.3-5.el10_1.8 · AlmaLinux:10Package registry (OSV)
almalinux:freerdp-devel2:3.10.3-5.el10_1.8 · AlmaLinux:10Package registry (OSV)
almalinux:freerdp-libs2:3.10.3-5.el10_1.8 · AlmaLinux:10Package registry (OSV)
almalinux:freerdp-server2:3.10.3-5.el10_1.8 · AlmaLinux:10Package registry (OSV)
almalinux:libwinpr2:3.10.3-5.el10_1.8 · AlmaLinux:10Package registry (OSV)
almalinux:libwinpr-devel2:3.10.3-5.el10_1.8 · AlmaLinux:10Package registry (OSV)
alpine:freerdp3.24.0-r0 · Alpine:v3.23Package registry (OSV)
debian:freerdp33.15.0+dfsg-2.1+deb13u2 · Debian:13Package registry (OSV)
opensuse:freerdp2.11.2-150600.4.18.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:freerdp22.11.7-6.1 · openSUSE:TumbleweedPackage registry (OSV)
red hat:freerdp2:3.10.3-5.el10_1.8 · Red Hat:enterprise_linux:10.1Package registry (OSV)
red hat:freerdp-debuginfo2:3.10.3-5.el10_1.8 · Red Hat:enterprise_linux:10.1Package registry (OSV)
red hat:freerdp-debugsource2:3.10.3-5.el10_1.8 · Red Hat:enterprise_linux:10.1Package registry (OSV)
red hat:freerdp-devel2:3.10.3-5.el10_1.8 · Red Hat:enterprise_linux:10.1Package registry (OSV)
red hat:freerdp-libs2:3.10.3-5.el10_1.8 · Red Hat:enterprise_linux:10.1Package registry (OSV)
red hat:freerdp-libs-debuginfo2:3.10.3-5.el10_1.8 · Red Hat:enterprise_linux:10.1Package registry (OSV)
red hat:freerdp-server2:3.10.3-5.el10_1.8 · Red Hat:enterprise_linux:10.1Package registry (OSV)
red hat:freerdp-server-debuginfo2:3.10.3-5.el10_1.8 · Red Hat:enterprise_linux:10.1Package registry (OSV)
red hat:libwinpr2:3.10.3-5.el10_1.8 · Red Hat:enterprise_linux:10.1Package registry (OSV)
red hat:libwinpr-debuginfo2:3.10.3-5.el10_1.8 · Red Hat:enterprise_linux:10.1Package registry (OSV)
red hat:libwinpr-devel2:3.10.3-5.el10_1.8 · Red Hat:enterprise_linux:10.1Package registry (OSV)
rocky linux:freerdp2:3.10.3-5.el10_1.8 · Rocky Linux:10Package registry (OSV)
suse:freerdp2.11.2-150600.4.18.1 · SUSE:Linux Enterprise Module for Package Hub 15 SP7Package registry (OSV)
suse:freerdp2.4.0-150400.3.47.1 · SUSE:Linux Enterprise Module for Package Hub 15 SP7Package registry (OSV)
suse:freerdp22.11.7-150700.3.14.1 · SUSE:Linux Enterprise Module for Package Hub 15 SP7Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-318060 days apartFreeRDP has a Heap Buffer Overflow in nsc_process_message() via Unchecked SURFACE_BITS_COMMAND Bitmap Dimensions
    37Monitor
  • CVE-2026-64620129 days apartFreeRDP before 3.28.0 Heap Buffer Overflow via crypto_rsa_common
    37Monitor
  • CVE-2026-67305141 days apartFreeRDP Windows Client before 3.29.0 Heap Buffer Overflow via Cliprdr
    37Monitor
  • CVE-2026-4442077 days apartFreeRDP cliprdr server heap-buffer-overflow via undersized capabilitySetLength in CB_CLIP_CAPS
    36Monitor
  • CVE-2026-4442177 days apartFreeRDP RDPGFX CacheToSurface heap-buffer-overflow via clamped-rectangle validation bypass
    35Monitor
  • CVE-2026-2468232 days apartFreeRDP has a Heap-buffer-overflow in audio_formats_free
    34Monitor

Not on record for this CVE: EPSS history · researcher credit · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-122 · Heap-based Buffer Overflow

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records