TI-2026-18957 Aliases CVE-2026-23533

FreeRDP has heap-buffer-overflow in clear_decompress_residual_data

HIGH 73CWE-122Published 2026-01-19 · Updated 2026-07-15

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: None
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Partial Red Hat: 24 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 version 3.21.0, a client-side heap buffer overflow occurs in the RDPGFX ClearCodec decode path when maliciously crafted residual data causes out-of-bounds writes during color output. A malicious server can trigger a client‑side heap buffer overflow, causing a crash (DoS) and potential heap corruption with code‑execution risk depending on allocator behavior and surrounding heap layout. Version 3.21.0 contains a patch for the issue.

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): 3.21.0Red Hat: 13 advisoriesRed Hat: 24 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Partial

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

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
FreeRDP	FreeRDP	before 3.21.0	3.21.0	Patch available	CNA

FreeRDP VendorFreeRDP Affected before 3.21.0 Fixed in 3.21.0 Patch available CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:freerdp:freerdp::::::::	before 3.21.0	Vulnerable	FreeRDP

cpe:2.3:a:freerdp:freerdp:*:*:*:*:*:*:*:* Versions before 3.21.0 Vulnerable ·FreeRDP

Remediation

Fix · CNA FreeRDP (FreeRDP) Fixed in 3.21.0

Red Hat 13 advisories

RHSA-2026:3037 Released 2026-02-23 · Red Hat rating Important
freerdp security update
- Red Hat CodeReady Linux Builder EUS (v.9.6) freerdp-devel-2:2.11.7-1.el9_6.1, libwinpr-devel-2:2.11.7-1.el9_6.1
- Red Hat Enterprise Linux AppStream EUS (v.9.6) freerdp-2:2.11.7-1.el9_6.1, freerdp-libs-2:2.11.7-1.el9_6.1, libwinpr-2:2.11.7-1.el9_6.1
RHSA-2026:3041 Released 2026-02-23 · Red Hat rating Important
freerdp security update
- Red Hat Enterprise Linux AppStream E4S (v.8.8) freerdp-2:2.2.0-12.el8_8.1, freerdp-libs-2:2.2.0-12.el8_8.1, libwinpr-2:2.2.0-12.el8_8.1 +1
- Red Hat Enterprise Linux AppStream TUS (v.8.8) freerdp-2:2.2.0-12.el8_8.1, freerdp-libs-2:2.2.0-12.el8_8.1, libwinpr-2:2.2.0-12.el8_8.1 +1
RHSA-2026:3036 Released 2026-02-23 · Red Hat rating Important
freerdp security update
- Red Hat Enterprise Linux AppStream AUS (v.8.6) freerdp-2:2.2.0-7.el8_6.1, freerdp-libs-2:2.2.0-7.el8_6.1, libwinpr-2:2.2.0-7.el8_6.1 +1
- Red Hat Enterprise Linux AppStream E4S (v.8.6) freerdp-2:2.2.0-7.el8_6.1, freerdp-libs-2:2.2.0-7.el8_6.1, libwinpr-2:2.2.0-7.el8_6.1 +1
- Red Hat Enterprise Linux AppStream TUS (v.8.6) freerdp-2:2.2.0-7.el8_6.1, freerdp-libs-2:2.2.0-7.el8_6.1, libwinpr-2:2.2.0-7.el8_6.1 +1

Show 10 more Red Hat advisories

RHSA-2026:3039 Released 2026-02-23 · Red Hat rating Important
freerdp security update
- Red Hat Enterprise Linux AppStream AUS (v. 8.2) freerdp-2:2.0.0-46.rc4.el8_2.6, freerdp-libs-2:2.0.0-46.rc4.el8_2.6, libwinpr-2:2.0.0-46.rc4.el8_2.6 +1
RHSA-2026:3038 Released 2026-02-23 · Red Hat rating Important
freerdp security update
- Red Hat Enterprise Linux AppStream AUS (v.8.4) freerdp-2:2.2.0-7.el8_4, freerdp-libs-2:2.2.0-7.el8_4, libwinpr-2:2.2.0-7.el8_4 +1
- Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) freerdp-2:2.2.0-7.el8_4, freerdp-libs-2:2.2.0-7.el8_4, libwinpr-2:2.2.0-7.el8_4 +1
RHSA-2026:2952 Released 2026-02-18 · Red Hat rating Important
freerdp security update
- Red Hat Enterprise Linux AppStream EUS (v. 10.0) freerdp-2:3.10.3-3.el10_0.1, freerdp-libs-2:3.10.3-3.el10_0.1, libwinpr-2:3.10.3-3.el10_0.1
- Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) freerdp-devel-2:3.10.3-3.el10_0.1, freerdp-server-2:3.10.3-3.el10_0.1, libwinpr-devel-2:3.10.3-3.el10_0.1
RHSA-2026:2824 Released 2026-02-17 · Red Hat rating Important
freerdp security update
- Red Hat Enterprise Linux AppStream E4S (v.9.2) freerdp-2:2.4.1-6.el9_2.2, freerdp-libs-2:2.4.1-6.el9_2.2, libwinpr-2:2.4.1-6.el9_2.2
RHSA-2026:2770 Released 2026-02-17 · Red Hat rating Important
freerdp security update
- Red Hat Enterprise Linux AppStream E4S (v.9.0) freerdp-2:2.4.1-3.el9_0, freerdp-libs-2:2.4.1-3.el9_0, libwinpr-2:2.4.1-3.el9_0
RHSA-2026:2736 Released 2026-02-16 · Red Hat rating Important
freerdp security update
- Red Hat CodeReady Linux Builder EUS (v.9.4) freerdp-devel-2:2.11.2-1.el9_4.1, libwinpr-devel-2:2.11.2-1.el9_4.1
- Red Hat Enterprise Linux AppStream EUS (v.9.4) freerdp-2:2.11.2-1.el9_4.1, freerdp-libs-2:2.11.2-1.el9_4.1, libwinpr-2:2.11.2-1.el9_4.1
RHSA-2026:2714 Released 2026-02-16 · Red Hat rating Important
freerdp security update
- Red Hat Enterprise Linux Server (v. 7 ELS) freerdp-2.1.1-5.el7_9.1, freerdp-libs-2.1.1-5.el7_9.1, freerdp-libs-2.1.1-5.el7_9.1.ppc +2
- Red Hat Enterprise Linux Server Optional (v. 7 ELS) freerdp-devel-2.1.1-5.el7_9.1, freerdp-devel-2.1.1-5.el7_9.1.ppc, libwinpr-devel-2.1.1-5.el7_9.1 +1
RHSA-2026:2222 Released 2026-02-09 · Red Hat rating Important
freerdp security update
- Red Hat Enterprise Linux AppStream (v. 10) freerdp-2:3.10.3-5.el10_1.1, freerdp-libs-2:3.10.3-5.el10_1.1, libwinpr-2:3.10.3-5.el10_1.1
- Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) freerdp-devel-2:3.10.3-5.el10_1.1, freerdp-server-2:3.10.3-5.el10_1.1, libwinpr-devel-2:3.10.3-5.el10_1.1
RHSA-2026:2081 Released 2026-02-05 · Red Hat rating Important
freerdp security update
- Red Hat Enterprise Linux AppStream (v. 8) freerdp-2:2.11.7-2.el8_10, freerdp-libs-2:2.11.7-2.el8_10, libwinpr-2:2.11.7-2.el8_10 +1
- Red Hat Enterprise Linux CRB (v. 8) freerdp-devel-2:2.11.7-2.el8_10
RHSA-2026:2048 Released 2026-02-05 · Red Hat rating Important
freerdp security update
- Red Hat Enterprise Linux AppStream (v. 9) freerdp-2:2.11.7-1.el9_7.1, freerdp-libs-2:2.11.7-1.el9_7.1, libwinpr-2:2.11.7-1.el9_7.1
- Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) freerdp-devel-2:2.11.7-1.el9_7.1, libwinpr-devel-2:2.11.7-1.el9_7.1

Vendor assessments

Red Hat

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

Product	Status	Plan or fix
Red Hat Enterprise Linux 6	Affected	No fix planned: Will not fix
Red Hat CodeReady Linux Builder EUS (v.9.4)	Fixed	RHSA-2026:2736
Red Hat CodeReady Linux Builder EUS (v.9.6)	Fixed	RHSA-2026:3037
Red Hat Enterprise Linux AppStream (v. 10)	Fixed	RHSA-2026:2222
Red Hat Enterprise Linux AppStream (v. 8)	Fixed	RHSA-2026:2081
Red Hat Enterprise Linux AppStream (v. 9)	Fixed	RHSA-2026:2048
Red Hat Enterprise Linux AppStream AUS (v. 8.2)	Fixed	RHSA-2026:3039
Red Hat Enterprise Linux AppStream AUS (v.8.4)	Fixed	RHSA-2026:3038
Red Hat Enterprise Linux AppStream AUS (v.8.6)	Fixed	RHSA-2026:3036
Red Hat Enterprise Linux AppStream E4S (v.8.6)	Fixed	RHSA-2026:3036
Red Hat Enterprise Linux AppStream E4S (v.8.8)	Fixed	RHSA-2026:3041
Red Hat Enterprise Linux AppStream E4S (v.9.0)	Fixed	RHSA-2026:2770
Red Hat Enterprise Linux AppStream E4S (v.9.2)	Fixed	RHSA-2026:2824
Red Hat Enterprise Linux AppStream EUS (v. 10.0)	Fixed	RHSA-2026:2952
Red Hat Enterprise Linux AppStream EUS (v.9.4)	Fixed	RHSA-2026:2736
Red Hat Enterprise Linux AppStream EUS (v.9.6)	Fixed	RHSA-2026:3037
Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)	Fixed	RHSA-2026:3038
Red Hat Enterprise Linux AppStream TUS (v.8.6)	Fixed	RHSA-2026:3036
Red Hat Enterprise Linux AppStream TUS (v.8.8)	Fixed	RHSA-2026:3041
Red Hat Enterprise Linux CRB (v. 8)	Fixed	RHSA-2026:2081
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)	Fixed	RHSA-2026:2222
Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)	Fixed	RHSA-2026:2048
Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)	Fixed	RHSA-2026:2952
Red Hat Enterprise Linux Server (v. 7 ELS)	Fixed	RHSA-2026:2714
Red Hat Enterprise Linux Server Optional (v. 7 ELS)	Fixed	RHSA-2026:2714

Timeline

2026-10-02 Threatist record created from CVE-2026-23533

References

Exploit 1

https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-32q9-m5qr-9j2v

Other 3

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