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TI-2026-39873 Aliases CVE-2026-55193

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

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
Partial Red Hat: 20 fixed, 1 without a fix

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, 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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00479 41st percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial FreeRDP (FreeRDP): 3.27.0Red Hat: 11 advisoriesRed Hat: 20 fixed, 1 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 3.27.03.27.0Patch 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-2026:74610 Released 2026-10-02 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux Server (v. 7 ELS) freerdp-2.1.1-5.el7_9.13, freerdp-libs-2.1.1-5.el7_9.13, freerdp-libs-2.1.1-5.el7_9.13.ppc +2
    • Red Hat Enterprise Linux Server Optional (v. 7 ELS) freerdp-devel-2.1.1-5.el7_9.13, freerdp-devel-2.1.1-5.el7_9.13.ppc, libwinpr-devel-2.1.1-5.el7_9.13 +1
  • RHSA-2026:74471 Released 2026-10-01 · Red Hat rating Critical
    freerdp security update
    • Red Hat Enterprise Linux AppStream EUS (v. 10.0) freerdp-2:3.10.3-3.el10_0.18, freerdp-libs-2:3.10.3-3.el10_0.18, libwinpr-2:3.10.3-3.el10_0.18
    • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) freerdp-devel-2:3.10.3-3.el10_0.18, freerdp-server-2:3.10.3-3.el10_0.18, libwinpr-devel-2:3.10.3-3.el10_0.18
  • RHSA-2026:74470 Released 2026-10-01 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream E4S (v.9.2) freerdp-2:2.4.1-6.el9_2.13, freerdp-libs-2:2.4.1-6.el9_2.13, libwinpr-2:2.4.1-6.el9_2.13
Show 8 more Red Hat advisories
  • RHSA-2026:73068 Released 2026-09-29 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream E4S (v.8.8) freerdp-2:2.2.0-12.el8_8.12, freerdp-libs-2:2.2.0-12.el8_8.12, libwinpr-2:2.2.0-12.el8_8.12 +1
    • Red Hat Enterprise Linux AppStream TUS (v.8.8) freerdp-2:2.2.0-12.el8_8.12, freerdp-libs-2:2.2.0-12.el8_8.12, libwinpr-2:2.2.0-12.el8_8.12 +1
  • RHSA-2026:73027 Released 2026-09-29 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream AUS (v.8.6) freerdp-2:2.2.0-7.el8_6.13, freerdp-libs-2:2.2.0-7.el8_6.13, libwinpr-2:2.2.0-7.el8_6.13 +1
    • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) freerdp-2:2.2.0-7.el8_6.13, freerdp-libs-2:2.2.0-7.el8_6.13, libwinpr-2:2.2.0-7.el8_6.13 +1
  • RHSA-2026:73026 Released 2026-09-29 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream AUS (v.8.4) freerdp-2:2.2.0-14.el8_4.4, freerdp-libs-2:2.2.0-14.el8_4.4, libwinpr-2:2.2.0-14.el8_4.4 +1
    • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) freerdp-2:2.2.0-14.el8_4.4, freerdp-libs-2:2.2.0-14.el8_4.4, libwinpr-2:2.2.0-14.el8_4.4 +1
  • RHSA-2026:72479 Released 2026-09-28 · Red Hat rating Important
    freerdp security update
    • Red Hat CodeReady Linux Builder EUS (v.9.6) freerdp-devel-2:2.11.7-1.el9_6.14, libwinpr-devel-2:2.11.7-1.el9_6.14
    • Red Hat Enterprise Linux AppStream EUS (v.9.6) freerdp-2:2.11.7-1.el9_6.14, freerdp-libs-2:2.11.7-1.el9_6.14, libwinpr-2:2.11.7-1.el9_6.14
  • RHSA-2026:72481 Released 2026-09-28 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream E4S (v.9.4) freerdp-2:2.11.2-1.el9_4.12, freerdp-libs-2:2.11.2-1.el9_4.12, libwinpr-2:2.11.2-1.el9_4.12
  • RHSA-2026:69387 Released 2026-09-21 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream (v. 8) freerdp-2:2.11.7-13.el8_10, freerdp-libs-2:2.11.7-13.el8_10, libwinpr-2:2.11.7-13.el8_10 +1
    • Red Hat Enterprise Linux CRB (v. 8) freerdp-devel-2:2.11.7-13.el8_10
  • RHSA-2026:66347 Released 2026-09-10 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream (v. 9) freerdp-2:2.11.7-7.el9_8.7, freerdp-libs-2:2.11.7-7.el9_8.7, libwinpr-2:2.11.7-7.el9_8.7
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) freerdp-devel-2:2.11.7-7.el9_8.7, libwinpr-devel-2:2.11.7-7.el9_8.7
  • RHSA-2026:66349 Released 2026-09-10 · Red Hat rating Important
    freerdp security update
    • Red Hat Enterprise Linux AppStream (v. 10) freerdp-2:3.10.3-12.el10_2.11, freerdp-libs-2:3.10.3-12.el10_2.11, libwinpr-2:3.10.3-12.el10_2.11
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) freerdp-devel-2:3.10.3-12.el10_2.11, freerdp-server-2:3.10.3-12.el10_2.11, libwinpr-devel-2:3.10.3-12.el10_2.11

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 CodeReady Linux Builder EUS (v.9.6)Fixed RHSA-2026:72479
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:66349
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2026:69387
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2026:66347
Red Hat Enterprise Linux AppStream AUS (v.8.4)Fixed RHSA-2026:73026
Red Hat Enterprise Linux AppStream AUS (v.8.6)Fixed RHSA-2026:73027
Red Hat Enterprise Linux AppStream E4S (v.8.8)Fixed RHSA-2026:73068
Red Hat Enterprise Linux AppStream E4S (v.9.2)Fixed RHSA-2026:74470
Red Hat Enterprise Linux AppStream E4S (v.9.4)Fixed RHSA-2026:72481
Red Hat Enterprise Linux AppStream EUS (v. 10.0)Fixed RHSA-2026:74471
Red Hat Enterprise Linux AppStream EUS (v.9.6)Fixed RHSA-2026:72479
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)Fixed RHSA-2026:73026
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6)Fixed RHSA-2026:73027
Red Hat Enterprise Linux AppStream TUS (v.8.8)Fixed RHSA-2026:73068
Red Hat Enterprise Linux CRB (v. 8)Fixed RHSA-2026:69387
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)Fixed RHSA-2026:66349
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)Fixed RHSA-2026:66347
Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)Fixed RHSA-2026:74471
Red Hat Enterprise Linux Server (v. 7 ELS)Fixed RHSA-2026:74610
Red Hat Enterprise Linux Server Optional (v. 7 ELS)Fixed RHSA-2026:74610

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-55193

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