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TI-2026-39874 Aliases CVE-2026-55194

FreeRDPHeap-buffer-overflow write in TS Gateway RPC RESPONSE reassembly due to alloc_hint capacity mismatch

Priority HIGH 73CWE-122Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Passive
Attack complexity
Low
Attack requirements
None
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-122 and the CVSS impact.

Summary

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, rpc_client_recv_fragment in libfreerdp/core/gateway/rpc_client.c ensures the response reassembly stream capacity using only the server-declared alloc_hint rather than the actual StubLength about to be written. A malicious TS Gateway can send a PTYPE_RESPONSE with a small alloc_hint and a much larger frag_length, causing Stream_Write to copy attacker-controlled stub data beyond the 4096-byte pdu->s buffer. This can crash the client and may permit code execution through heap corruption. This issue is fixed in version 3.27.0.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00619 49th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed FreeRDP (FreeRDP): 3.27.0Red Hat: 11 advisories

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 3.27.03.27.0Patch availableCNA
  • FreeRDP VendorFreeRDP Affected before 3.27.0 Fixed in 3.27.0 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:freerdp:freerdp:*:*:*:*:*:*:*:*before 3.27.0VulnerableFreeRDP
  • cpe:2.3:a:freerdp:freerdp:*:*:*:*:*:*:*:* Versions before 3.27.0 Vulnerable ·FreeRDP

Remediation

  • Fix · CNA FreeRDP (FreeRDP) Fixed in 3.27.0

Red Hat 11 advisories

  • RHSA-2026:71387 Released 2026-09-24 · Red Hat rating Important
    freerdp security update
    • Red Hat CodeReady Linux Builder EUS (v.9.6) freerdp-devel-2:2.11.7-1.el9_6.13, libwinpr-devel-2:2.11.7-1.el9_6.13
    • Red Hat Enterprise Linux AppStream EUS (v.9.6) freerdp-2:2.11.7-1.el9_6.13, freerdp-libs-2:2.11.7-1.el9_6.13, libwinpr-2:2.11.7-1.el9_6.13
  • RHSA-2026:71390 Released 2026-09-24 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream E4S (v.9.4) freerdp-2:2.11.2-1.el9_4.11, freerdp-libs-2:2.11.2-1.el9_4.11, libwinpr-2:2.11.2-1.el9_4.11
  • RHSA-2026:71388 Released 2026-09-24 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream E4S (v.9.2) freerdp-2:2.4.1-6.el9_2.12, freerdp-libs-2:2.4.1-6.el9_2.12, libwinpr-2:2.4.1-6.el9_2.12
Show 8 more Red Hat advisories
  • RHSA-2026:68707 Released 2026-09-17 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux Server (v. 7 ELS) freerdp-2.1.1-5.el7_9.12, freerdp-libs-2.1.1-5.el7_9.12, freerdp-libs-2.1.1-5.el7_9.12.ppc +2
    • Red Hat Enterprise Linux Server Optional (v. 7 ELS) freerdp-devel-2.1.1-5.el7_9.12, freerdp-devel-2.1.1-5.el7_9.12.ppc, libwinpr-devel-2.1.1-5.el7_9.12 +1
  • RHSA-2026:68706 Released 2026-09-17 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream EUS (v. 10.0) freerdp-2:3.10.3-3.el10_0.16, freerdp-libs-2:3.10.3-3.el10_0.16, libwinpr-2:3.10.3-3.el10_0.16
    • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) freerdp-devel-2:3.10.3-3.el10_0.16, freerdp-server-2:3.10.3-3.el10_0.16, libwinpr-devel-2:3.10.3-3.el10_0.16
  • RHSA-2026:66282 Released 2026-09-10 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream E4S (v.8.8) freerdp-2:2.2.0-12.el8_8.11, freerdp-libs-2:2.2.0-12.el8_8.11, libwinpr-2:2.2.0-12.el8_8.11 +1
    • Red Hat Enterprise Linux AppStream TUS (v.8.8) freerdp-2:2.2.0-12.el8_8.11, freerdp-libs-2:2.2.0-12.el8_8.11, libwinpr-2:2.2.0-12.el8_8.11 +1
  • RHSA-2026:66281 Released 2026-09-10 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream AUS (v.8.6) freerdp-2:2.2.0-7.el8_6.12, freerdp-libs-2:2.2.0-7.el8_6.12, libwinpr-2:2.2.0-7.el8_6.12 +1
    • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) freerdp-2:2.2.0-7.el8_6.12, freerdp-libs-2:2.2.0-7.el8_6.12, libwinpr-2:2.2.0-7.el8_6.12 +1
  • RHSA-2026:65855 Released 2026-09-09 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream AUS (v.8.4) freerdp-2:2.2.0-14.el8_4.3, freerdp-libs-2:2.2.0-14.el8_4.3, libwinpr-2:2.2.0-14.el8_4.3 +1
    • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) freerdp-2:2.2.0-14.el8_4.3, freerdp-libs-2:2.2.0-14.el8_4.3, libwinpr-2:2.2.0-14.el8_4.3 +1
  • RHSA-2026:62571 Released 2026-09-02 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream (v. 8) freerdp-2:2.11.7-12.el8_10, freerdp-libs-2:2.11.7-12.el8_10, libwinpr-2:2.11.7-12.el8_10 +1
    • Red Hat Enterprise Linux CRB (v. 8) freerdp-devel-2:2.11.7-12.el8_10
  • RHSA-2026:61378 Released 2026-08-31 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream (v. 10) freerdp-2:3.10.3-12.el10_2.10, freerdp-libs-2:3.10.3-12.el10_2.10, libwinpr-2:3.10.3-12.el10_2.10
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) freerdp-devel-2:3.10.3-12.el10_2.10, freerdp-server-2:3.10.3-12.el10_2.10, libwinpr-devel-2:3.10.3-12.el10_2.10
  • RHSA-2026:61379 Released 2026-08-31 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream (v. 9) freerdp-2:2.11.7-7.el9_8.6, freerdp-libs-2:2.11.7-7.el9_8.6, libwinpr-2:2.11.7-7.el9_8.6
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) freerdp-devel-2:2.11.7-7.el9_8.6, libwinpr-devel-2:2.11.7-7.el9_8.6

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
Red Hat CodeReady Linux Builder EUS (v.9.6)Fixed RHSA-2026:71387
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:61378
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2026:62571
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2026:61379
Red Hat Enterprise Linux AppStream AUS (v.8.4)Fixed RHSA-2026:65855
Red Hat Enterprise Linux AppStream AUS (v.8.6)Fixed RHSA-2026:66281
Red Hat Enterprise Linux AppStream E4S (v.8.8)Fixed RHSA-2026:66282
Red Hat Enterprise Linux AppStream E4S (v.9.2)Fixed RHSA-2026:71388
Red Hat Enterprise Linux AppStream E4S (v.9.4)Fixed RHSA-2026:71390
Red Hat Enterprise Linux AppStream EUS (v. 10.0)Fixed RHSA-2026:68706
Red Hat Enterprise Linux AppStream EUS (v.9.6)Fixed RHSA-2026:71387
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)Fixed RHSA-2026:65855
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6)Fixed RHSA-2026:66281
Red Hat Enterprise Linux AppStream TUS (v.8.8)Fixed RHSA-2026:66282
Red Hat Enterprise Linux CRB (v. 8)Fixed RHSA-2026:62571
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)Fixed RHSA-2026:61378
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)Fixed RHSA-2026:61379
Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)Fixed RHSA-2026:68706
Red Hat Enterprise Linux Server (v. 7 ELS)Fixed RHSA-2026:68707
Red Hat Enterprise Linux Server Optional (v. 7 ELS)Fixed RHSA-2026:68707
Not affected: 1 product
  • Red Hat Enterprise Linux 6

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-55194

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