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CVE-2026-55193· NVD / CVE Program· CNA GitHub_M

FreeRDP: Heap-buffer-overflow write in TS Gateway RPC fragment receive due to uncapped bind_ack max_xmit_frag

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, FreeRDP clients using TS Gateway accept a server-controlled max_xmit_frag value in libfreerdp/core/gateway/rpc_bind.c without bounding it to the 4088-byte ReceiveFragment allocation. A malicious gateway can advertise 65535 and then send a response fragment of the same length, causing rpc_channel_read in libfreerdp/core/gateway/rpc.c to write up to 65535 bytes into the smaller ReceiveFragment buffer. This can crash the client and may permit code execution through attacker-controlled heap corruption. This issue is fixed in version 3.27.0.

HighCVSS 8.7 · v4.0—No exploit Fix available
Published
Aug 19, 2026
Updated
Sep 29, 2026
EPSS
0.4% · 37th percentile
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Action score

34

Monitor

Low priority for now.

CVSS
34 / 40 · 8.7 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
8.7
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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

Noroxi analysis

No Noroxi analysis for this record yet

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Affected systems

VendorProduct
freerdpfreerdp

Affected versions

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

  • freerdp freerdpbefore 3.27.0

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

    • < 3.27.0affected

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10freerdpbefore 2:3.10.3-12.el10_2.112:3.10.3-12.el10_2.11
AlmaLinux:10freerdp-develbefore 2:3.10.3-12.el10_2.112:3.10.3-12.el10_2.11
AlmaLinux:10freerdp-libsbefore 2:3.10.3-12.el10_2.112:3.10.3-12.el10_2.11
AlmaLinux:10freerdp-serverbefore 2:3.10.3-12.el10_2.112:3.10.3-12.el10_2.11
AlmaLinux:10libwinprbefore 2:3.10.3-12.el10_2.112:3.10.3-12.el10_2.11
AlmaLinux:10libwinpr-develbefore 2:3.10.3-12.el10_2.112:3.10.3-12.el10_2.11
AlmaLinux:8freerdpbefore 2:2.11.7-13.el8_102:2.11.7-13.el8_10
AlmaLinux:8freerdp-develbefore 2:2.11.7-13.el8_102:2.11.7-13.el8_10
AlmaLinux:8freerdp-libsbefore 2:2.11.7-13.el8_102:2.11.7-13.el8_10
AlmaLinux:8libwinprbefore 2:2.11.7-13.el8_102:2.11.7-13.el8_10
AlmaLinux:8libwinpr-develbefore 2:2.11.7-13.el8_102:2.11.7-13.el8_10
AlmaLinux:9freerdpbefore 2:2.11.7-7.el9_8.72:2.11.7-7.el9_8.7
AlmaLinux:9freerdp-develbefore 2:2.11.7-7.el9_8.72:2.11.7-7.el9_8.7
AlmaLinux:9freerdp-libsbefore 2:2.11.7-7.el9_8.72:2.11.7-7.el9_8.7
AlmaLinux:9libwinprbefore 2:2.11.7-7.el9_8.72:2.11.7-7.el9_8.7
AlmaLinux:9libwinpr-develbefore 2:2.11.7-7.el9_8.72:2.11.7-7.el9_8.7
Debian:12freerdp2all versions—
Debian:13freerdp3all versions—
Debian:14freerdp3before 3.27.0+dfsg-13.27.0+dfsg-1
openSUSE:Tumbleweedfreerdpbefore 3.27.1-1.13.27.1-1.1
Red Hat:enterprise_linux:10.2freerdpbefore 2:3.10.3-12.el10_2.112:3.10.3-12.el10_2.11
Red Hat:enterprise_linux:10.2freerdp-debuginfobefore 2:3.10.3-12.el10_2.112:3.10.3-12.el10_2.11
Red Hat:enterprise_linux:10.2freerdp-debugsourcebefore 2:3.10.3-12.el10_2.112:3.10.3-12.el10_2.11
Red Hat:enterprise_linux:10.2freerdp-develbefore 2:3.10.3-12.el10_2.112:3.10.3-12.el10_2.11

+68

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 gdi_Bitmap_Decompress
    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 co
    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 update_read_bitmap_
    41Plan
  • CVE-2018-8785FreeRDP prior to version 2.0.0-rc4 contains a Heap-Based Buffer Overflow in function zgfx_decompress() that results in a memory corruption a
    41Plan
  • CVE-2018-8784FreeRDP prior to version 2.0.0-rc4 contains a Heap-Based Buffer Overflow in function zgfx_decompress_segment() that results in a memory corr
    41Plan
  • CVE-2024-32460FreeRDP Out-Of-Bounds Read in interleaved_decompress
    40Plan

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 FreeRDP3.27.0 · descriptionVendor (CNA)
almalinux:freerdp2:2.11.7-7.el9_8.7 · AlmaLinux:9Package registry (OSV)
almalinux:freerdp-devel2:2.11.7-7.el9_8.7 · AlmaLinux:9Package registry (OSV)
almalinux:freerdp-libs2:2.11.7-7.el9_8.7 · AlmaLinux:9Package registry (OSV)
almalinux:freerdp-server2:3.10.3-12.el10_2.11 · AlmaLinux:10Package registry (OSV)
almalinux:libwinpr2:2.11.7-7.el9_8.7 · AlmaLinux:9Package registry (OSV)
almalinux:libwinpr-devel2:2.11.7-7.el9_8.7 · AlmaLinux:9Package registry (OSV)
debian:freerdp33.27.0+dfsg-1 · Debian:14Package registry (OSV)
opensuse:freerdp3.27.1-1.1 · openSUSE:TumbleweedPackage registry (OSV)
red hat:freerdp2:2.11.7-7.el9_8.7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:freerdp-debuginfo2:2.11.7-7.el9_8.7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:freerdp-debugsource2:2.11.7-7.el9_8.7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:freerdp-devel2:2.11.7-7.el9_8.7 · Red Hat:enterprise_linux:9::crbPackage registry (OSV)
red hat:freerdp-libs2:2.11.7-7.el9_8.7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:freerdp-libs-debuginfo2:2.11.7-7.el9_8.7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:freerdp-server2:3.10.3-12.el10_2.11 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:freerdp-server-debuginfo2:3.10.3-12.el10_2.11 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:libwinpr2:2.11.7-7.el9_8.7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:libwinpr-debuginfo2:2.11.7-7.el9_8.7 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:libwinpr-devel2:2.11.7-7.el9_8.7 · Red Hat:enterprise_linux:9::crbPackage registry (OSV)
rocky linux:freerdp2:2.11.7-7.el9_8.7 · Rocky Linux:9Package 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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

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

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

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

  • CVE-2026-31883159 days apartFreeRDP has a `size_t` underflow in ADPCM decoder leads to heap-buffer-overflow write
    39Monitor
  • CVE-2026-6730518 days apartFreeRDP Windows Client before 3.29.0 Heap Buffer Overflow via Cliprdr
    37Monitor
  • CVE-2026-6462030 days apartFreeRDP before 3.28.0 Heap Buffer Overflow via crypto_rsa_common
    37Monitor
  • CVE-2026-31806159 days apartFreeRDP has a Heap Buffer Overflow in nsc_process_message() via Unchecked SURFACE_BITS_COMMAND Bitmap Dimensions
    37Monitor
  • CVE-2026-4442082 days apartFreeRDP cliprdr server heap-buffer-overflow via undersized capabilitySetLength in CB_CLIP_CAPS
    35Monitor
  • CVE-2026-4442182 days apartFreeRDP RDPGFX CacheToSurface heap-buffer-overflow via clamped-rectangle validation bypass
    35Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

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

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
P
Scope
X

Weakness class (CWE)

CWE-122 · Heap-based Buffer Overflow

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/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

nvd-secondary

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

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

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

All records