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TI-2026-40295 Aliases CVE-2026-55827

FreeRDP: Heap out-of-bounds write in RemoteFX (RFX) Cache Bitmap V3 decode

Priority HIGH 73CWE-131Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 4 fixed, 2 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-131 and the CVSS impact.

Summary

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.1, FreeRDP clients launched with the non-default /cache:codec:rfx option pass desktop stride and height to RemoteFX decoding for Cache Bitmap V3 data while allocating bitmap->data only for the smaller DstWidth and DstHeight in gdi_Bitmap_Decompress, allowing a malicious RDP server to trigger a heap out-of-bounds write with attacker-controlled offset and content. This issue is fixed in version 3.27.1.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00533 45th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial FreeRDP (FreeRDP): 3.27.1Red Hat: 2 advisoriesRed Hat: 4 fixed, 2 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
FreeRDPFreeRDPbefore 3.27.13.27.1Patch availableCNA
  • FreeRDP VendorFreeRDP Affected before 3.27.1 Fixed in 3.27.1 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:freerdp:freerdp:*:*:*:*:*:*:*:*before 3.27.1VulnerableFreeRDP
  • cpe:2.3:a:freerdp:freerdp:*:*:*:*:*:*:*:* Versions before 3.27.1 Vulnerable ·FreeRDP

Remediation

  • Fix · CNA FreeRDP (FreeRDP) Fixed in 3.27.1

Red Hat 2 advisories

  • RHSA-2026:54667 Released 2026-08-13 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream EUS (v. 10.0) freerdp-2:3.10.3-3.el10_0.10, freerdp-libs-2:3.10.3-3.el10_0.10, libwinpr-2:3.10.3-3.el10_0.10
    • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) freerdp-devel-2:3.10.3-3.el10_0.10, freerdp-server-2:3.10.3-3.el10_0.10, libwinpr-devel-2:3.10.3-3.el10_0.10
  • RHSA-2026:50747 Released 2026-08-05 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream (v. 10) freerdp-2:3.10.3-12.el10_2.7, freerdp-libs-2:3.10.3-12.el10_2.7, libwinpr-2:3.10.3-12.el10_2.7
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) freerdp-devel-2:3.10.3-12.el10_2.7, freerdp-server-2:3.10.3-12.el10_2.7, libwinpr-devel-2:3.10.3-12.el10_2.7

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 7AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:50747
Red Hat Enterprise Linux AppStream EUS (v. 10.0)Fixed RHSA-2026:54667
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)Fixed RHSA-2026:50747
Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)Fixed RHSA-2026:54667
Not affected: 2 products
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-55827

References

Exploit 1

Patch 2

Other 1

  • TI-2026-85092 Use-after-free in FreeRDP rdpgfx channel close handling CVSS 4.0CRITICAL 9.3
  • TI-2026-85091 Out-of-bounds write in FreeRDP proxy via bitmap cache v2 capability CVSS 4.0CRITICAL 9.3
  • TI-2026-24435 FreeRDP has a `size_t` underflow in ADPCM decoder leads to heap-buffer-overflow write CVSS 3.1CRITICAL 9.8
  • TI-2023-21373 Out-Of-Bounds Write in FreeRDP CVSS 3.1CRITICAL 9.8
  • TI-2022-08692 Server side NTLM does not properly check parameters in FreeRDP CVSS 3.1CRITICAL 9.1
  • TI-2023-21374 Out-Of-Bounds Read in FreeRDP CVSS 3.1CRITICAL 9.1
See all 336 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences