8.8 CVE-2026-26965

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, in the RLE planar decode path, `planar_decompress_plane_rle()` writes into `pDstData` at `((nYDst+y) * nDstStep) + (4*nXDst) + nChannel` without verifying that `(nYDst+nSrcHeight)` fits in the destination height or that `(nXDst+nSrcWidth)` fits in the destination stride. When `TempFormat != DstFormat`, `pDstData` becomes `planar->pTempData` (sized for the desktop), while `nYDst` is only validated against the **surface** by `is_within_surface()`. A malicious RDP server can exploit this to perform a heap out-of-bounds write with attacker-controlled offset and pixel data on any connecting FreeRDP client. The OOB write reaches up to 132,096 bytes past the temp buffer end, and on the brk heap (desktop ≤ 128×128), an adjacent `NSC_CONTEXT` struct's `decode` function pointer is overwritten with attacker-controlled pixel data — control-flow–relevant corruption (function pointer overwritten) demonstrated under deterministic heap layout (`nsc->decode = 0xFF414141FF414141`). Version 3.23.0 fixes the vulnerability.
https://nvd.nist.gov/vuln/detail/CVE-2026-26965

Categories

CWE-787 : Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer. At the point when the product writes data to an invalid location, it is likely that a separate weakness already occurred earlier. For example, the product might alter an index, perform incorrect pointer arithmetic, initialize or release memory incorrectly, etc., thus referencing a memory location outside the buffer. Often used to describe the consequences of writing to memory outside the bounds of a buffer, or to memory that is otherwise invalid. This weakness can be detected using dynamic tools and techniques that interact with the software using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The software's operation may slow down, but it should not become unstable, crash, or generate incorrect results. Use tools that are integrated duringcompilation to insert runtime error-checking mechanismsrelated to memory safety errors, such as AddressSanitizer(ASan) for C/C++ [REF-1518]. Replace unbounded copy functions with analogous functions that support length arguments, such as strcpy with strncpy. Create these if they are not available. Font rendering library does not properlyhandle assigning a signed short value to an unsignedlong (CWE-195), leading to an integer wraparound(CWE-190), causing too small of a buffer (CWE-131),leading to an out-of-bounds write(CWE-787). The reference implementation code for a Trusted Platform Module does not implement length checks on data, allowing for an attacker to write 2 bytes past the end of a buffer. Chain: insufficient input validation (CWE-20) in browser allows heap corruption (CWE-787), as exploited in the wild per CISA KEV. GPU kernel driver allows memory corruption because a user can obtain read/write access to read-only pages, as exploited in the wild per CISA KEV. Chain: integer truncation (CWE-197) causes small buffer allocation (CWE-131) leading to out-of-bounds write (CWE-787) in kernel pool, as exploited in the wild per CISA KEV. Out-of-bounds write in kernel-mode driver, as exploited in the wild per CISA KEV. Escape from browser sandbox using out-of-bounds write due to incorrect bounds check, as exploited in the wild per CISA KEV. Memory corruption in web browser scripting engine, as exploited in the wild per CISA KEV. chain: mobile phone Bluetooth implementation does not include offset when calculating packet length (CWE-682), leading to out-of-bounds write (CWE-787) Chain: compiler optimization (CWE-733) removes or modifies code used to detect integer overflow (CWE-190), allowing out-of-bounds write (CWE-787). malformed inputs cause accesses of uninitialized or previously-deleted objects, leading to memory corruption chain: -1 value from a function call was intended to indicate an error, but is used as an array index instead. Unchecked length of SSLv2 challenge value leads to buffer underflow. Buffer underflow from a small size value with a large buffer (length parameter inconsistency, CWE-130) Chain: integer signedness error (CWE-195) passes signed comparison, leading to heap overflow (CWE-122) Classic stack-based buffer overflow in media player using a long entry in a playlist Heap-based buffer overflow in media player using a long entry in a playlist

References

 

AFFECTED (from MITRE)

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Vendor	Product	Versions
FreeRDP	FreeRDP	< 3.23.0 [affected]
© 2022 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation.

CPE

cpe	start	end
Configuration 1
cpe:2.3:a:freerdp:freerdp:*:*:*:*:*:*:*:*		< 3.23.0

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REMEDIATION

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Patch

Url
https://github.com/FreeRDP/FreeRDP/commit/a0be5cb87d760bb1c803ad1bb835aa1e73e...
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-5vgf-mw4f-r33h

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EXPLOITS

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Exploit-db.com

id	description	date
No known exploits

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POC Github

Url
No known exploits

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Other Nist (github, ...)

Url
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-5vgf-mw4f-r33h

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CAPEC

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Common Attack Pattern Enumerations and Classifications

id	description	severity
No entry

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