FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.26.0, a malicious RDP server can trigger a heap-buffer-overflow write in the FreeRDP client by sending crafted RDPGFX PDUs. The bug is in gdi_CacheToSurface: it validates a destination rectangle that is clamped to UINT16_MAX, but then performs the copy using the original cacheEntry->width/height. This can cause a large out-of-bounds heap write and may lead to client crashes or code execution. This bug is reachable from a malicious RDP server, but only when the client has RDPGFX enabled. This vulnerability is fixed in 3.26.0.

The remote Redhat Enterprise Linux 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:36203 advisory.

    FreeRDP is a free implementation of the Remote Desktop Protocol (RDP), released under the Apache license.
    The xfreerdp client can connect to RDP servers such as Microsoft Windows machines, xrdp, and VirtualBox.

    Security Fix(es):

    * freerdp: FreeRDP: Remote code execution via heap-buffer-overflow in gdi_CacheToSurface (CVE-2026-40033)

    * freerdp: FreeRDP: Arbitrary code execution or denial of service via heap use-after-free in RDPEAR NDR     parser (CVE-2026-44422)

    * freerdp: FreeRDP: Out-of-bounds write in planar bitmap decoder allows arbitrary code execution     (CVE-2026-45700)

    * freerdp: FreeRDP: Arbitrary code execution via crafted RDPGFX PDUs (CVE-2026-44421)

    * freerdp: FreeRDP: Arbitrary code execution and denial of service via heap-buffer-overflow     (CVE-2026-44420)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote SUSE Linux SLES16 / SLES_SAP16 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:22194-1 advisory.

    This update for freerdp fixes the following issues

    Update to version 3.26.0:

    - CVE-2026-33982: heap-buffer-overflow READ vulnerability at 24 bytes before the allocation, in       winpr_aligned_offset_recalloc() (bsc#1261222).
    - CVE-2026-33985: FreeRDP: Information disclosure via heap memory out of bounds read (bsc#1261217).
    - CVE-2026-33986: heap OOB write due to H.264 YUV buffer dimension desync (bsc#1261223).
    - CVE-2026-33987: heap OOB write due to persistent cache bmpSize desync (bsc#1261226).
    - CVE-2026-33995: double-free vulnerability in kerberos_AcceptSecurityContext() and       kerberos_InitializeSecurityContextA() (bsc#1261227).
    - CVE-2026-40033: heap buffer overflow in `gdi_CacheToSurface` allows attackers to cause a denial of     service or achieve       remote execute code (bsc#1266317).
    - CVE-2026-40254: off-by-one in contains_dotdot() allows drive channel path traversal (bsc#1262743).
    - CVE-2026-44420: Prior to 3.26.0, a malicious RDP client can trigger a heap-buffer-overflow write in     FreeRDP's server-       side clipboard (cliprdr) channel (bsc#1267008).
    - CVE-2026-44421: Prior to 3.26.0, a malicious RDP server can trigger a heap-buffer-overflow write in the     FreeRDP client       by sending crafted RDPGFX PDUs (bsc#1267009).
    - CVE-2026-44422: Prior to 3.26.0, a malicious-server-triggerable heap use-after-free / double-free in the     FreeRDP       client's RDPEAR authentication-redirection path exists (bsc#1267010).
    - CVE-2026-45700: n attacker can bypass the check with a large nDstStep and a large nXDst, causing       planar_decompress_plane_rle() to write past the end of pTempData (bsc#1267011).

    Changes:

     * cmake: Findyuv: Use correct pkgconfig name (#12666)
     * Remove deallocator attribute from rfx_message_free (#12681)
     * [winpr,utils] improve winpr/ntlm.h (#12677)
     * rdpecam-v4l: stop the capture thread when streaming is cleared (#12690)
     * fix(winpr,ncrypt): support PIV retired key slots for smartcard logon (#12684)
     * [core,instance] fix deprecation guards (#12691)
     * [ci,alt-arch] enable internal MD4, MD5 and RC4 (#12692)
     * Add VideoToolbox H.264 support for ffmpeg (#12694)
     * [client,common] add /args-from:file: syntax (#12697)
     * [ci,freebsd] update freebsd builds (#12698, #12700, #12701, #12702)
     * [client, android] UI modernization, SQLCipher and more (#12685, #12686, #12687, #12730,
     * #12731, #12736, #12737, #12688)
     * [cmake,deps] use alias target for sso-mib (#12706)
     * [core,settings] add auto reconnect triggered flag (#12709)
     * Force YUV420P when videotoolbox is used (#12711)
     * Release cleanups (#12712)
     * [gdi,gfx] fix bounds checks and proxy unit tests (#12713)
     * Improved input checks (#12714)
     * [winpr,utils] add unit tests for command line parser (#12716)
     * Cmdline fixes (#12717)
     * [codec,planar] fix bounds checks (#12718)
     * [client,common] add freerdp_client_settings_parse_command_line_argume... (#12724)
     * [winpr,sspi] clean up ntlm code (#12732)
     * Experimental AV1 support has been added. This currently works only with FreeRDP based servers.
     * Most notably there is now support for [MS-RDPEWA] (FIDO2 redirection)
     * Android client received a (small) facelift
     * Improved SDL3 client drawing performance
     * Console output support for SDL3 (windows) and windows native client
     * RDP proxy now supports NSCodec and RFX modes.
     * RDP PRoxy now has smartcard emulation and SAM file support (via config file)
     * Smartcard KSP support for NLA authentication
     * [winpr,wlog] add WLog_SetGlobalPrefix (#12497)
     * [channels,video] fix wrong cast (#12511)
     * [codec,openh264] reject encoder ABI mismatch on runtime-loaded library (#12510)
     * [client,sdl] create a copy of rdpPointer (#12512)
     * [codec,video] properly pass intermediate format (#12518)
     * [utils, signal] lazily initialize Windows CRITICAL_SECTION to match POSIX static mutex behavior     (#12520)
     * winpr: improve libunwind backtraces (#12530)
     * [server,shadow] remember selected caps (#12528)
     * Zero credential data before free in NLA and NTLM context (#12532)
     * [server,proxy] ignore missing client in input channel (#12536)
     * [server,proxy] ignore rdpdr messages (#12537)
     * [winpr,sspi] improve kerberos logging (#12538)
     * Codec fixes (#12542)
     * [winpr,sspi] Fix context nullptr handling (#12543)
     * Dev 3.24.3 dev0 (#12545)
     * Fix memory leak in gdi_create_bitmap() on gdi_CreateBitmap failure (libfreerdp/gdi/graphics.c) (#12547)
     * Fix memory leak in vgids_read_do_fkt() on Stream_New failure     (libfreerdp/emu/scard/smartcard_virtual_gids.c) (#12548)
     * Proxy config improve (#12549)
     * Proxy config improve (#12550)
     * [client,sdl] clamp cursor hotspot (#12553)
     * RFC: Research/av1 codec extension (#12527)
     * [winpr,kerberos] fix krb_log_context_encryption (#12555)
     * [client,sdl] fix global init return check (#12558)
     * Fix remote credential with windows11h2 (#12560)
     * Proxy scard auth improvements (#12561)
     * [winpr,sspi] guard krb5_get_etype_info (#12562)
     * [utils,smartcard] fix STATUS_BUFFER_TOO_SMALL (#12564)
     * [client,common] do not manipulate security settings for smartcard-logon (#12567)
     * [channels,audin] fix regression for microphone (#12570)
     * [client,sdl] add SDL_KMOD_MODE and SDL_KMOD_LEVEL5 (#12569)
     * Fix unbound strlen on slotDescription (#12571)
     * build: Update FindFFmpeg.cmake to support Apple frameworks with 'lib' prefix (#12565)
     * [channels,rdpewa] add WebAuthn virtual channel support (#12572)
     * [core] fix freerdp_get_nla_sspi_error always returning 0 on client (#12574)
     * [ci] enable rdpewa channel (#12576)
     * small refactoring (#12578)
     * Rdpewa unify notifications (#12581)
     * [client,sdl] fix crash when clicking 'cancel' on PIN popup (#12580)
     * [channels,drive] refine bounds checks (#12584)
     * fix: smartcard logon with ECC keys and minidriver-assigned container names (#12585)
     * Various papercuts (#12583)
     * fix: console output on Windows client (#12573)
     * [winpr,crt] dump stack on aligned memory errors (#12588)
     * [client,x11] keep scancode input for Ctrl/Alt/Super combinations in /kbd:unicode mode (#12590)
     * [codec,progressive] fix underflow guard in progressive_rfx_quant_sub (#12592)
     * fix: wfreerdp floatbar visibility (#12594)
     * [winpr,json] return a copy from WINPR_JSON_Print* (#12595)
     * [client,sdl] drop WITH_DEBUG_SDL_EVENTS (#12599)
     * Ncrypt and asn1 cleanup (#12604)
     * Video channel fix (#12593)
     * [codec,h264] fix media foundation backend (#12606)
     * fix(sdl): detect Hyprland and river in tryFallback() (#12608)
     * Proxy stress fixes (#12597)
     * Add new fuzzer tests (#12613)
     * fix(sdl): use SDL_Renderer instead of software surfaces (#12607)
     * fix(sdl): BFS neighbor walk pop/begin mismatch in addOrUpdateDisplay (#12614)
     * fix(sdl): promote first monitor as primary when subset excludes primary (#12618)
     * [ci,android] default to only aarch64 (#12622)
     * Fix process exit code on non-pidfd platforms (macOS, BSD)#12534) (#12586)
     * warning cleanups (#12626)
     * fix: prevent PostQuitMessage in RemoteApp WM_DESTROY handler (#12629)
     * [winpr,ntlm] fix message cleanup across the SSPI lifecycle (#12609)
     * Code bug fixes (#12632)
     * Oss fixes (#12633)
     * [client,android] add an option to enable keeping screen on when connected (#12630)
     * [client, android] Fix layout overlaps, migrate to AndroidX, and update UI components (#12628)
     * Proxy config tests (#12636)
     * Proxy config optional targethost (#12637)
     * [client,sdl] set SDL_HINT_SCREENSAVER_INHIBIT_ACTIVITY_NAME (#12639)
     * Nightly deb fix (#12640, #12641, #12649, #12650, #12642, #12643)
     * [winpr,input] fix korean keyboard mapping (#12646)
     * [client,sdl] set hints before SDL_Init (#12644)
     * Sdl inhibit option (#12647)
     * [client,X11] fix residual race in xf_clipboard_formats_free (#12648)
     * (sdl3): Fix oversized window on HiDPI Wayland (#12635)
     * [cache,bitmap] fix off-by-one in bitmap_cache_put bounds check (#12651)
     * [winpr,sspi] free fields buffer immediately (#12654)
     * [codec,dsp] fix fencepost error in dsp_ima_clamp_step (#12655)
     * RDPECAM MJPEG support
     * Support for FDK-AAC for sound and microphone redirection
     * Support timezones as JSON resources
     * Rely preferably on pkgconfig to pull devel packages instead of
     * A new option /cert that unifies all certificate related options (gh#FreeRDP/FreeRDP#5880)

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1822 advisory.

    FreeRDP before 3.26.0 contains a heap-buffer-overflow vulnerability in gdi_CacheToSurface that allows     remote attackers to write out-of-bounds heap memory. The vulnerability occurs because rectangle validation     clamps coordinates to UINT16_MAX but performs copy operations using unclamped cache entry dimensions,     enabling malicious RDP servers to trigger large out-of-bounds writes and potentially achieve remote code     execution or client crash. (CVE-2026-40033)

    FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.26.0, a malicious RDP client     can trigger a heap-buffer-overflow write in FreeRDP's server-side clipboard (cliprdr) channel by sending a     CB_CLIP_CAPS PDU with a too-small capabilitySetLength. This can crash the server process (remote DoS) and     may be exploitable for code execution because it corrupts heap memory. This vulnerability is fixed in     3.26.0. (CVE-2026-44420)

    FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.26.0, a malicious RDP server     can trigger a heap-buffer-overflow write in the FreeRDP client by sending crafted RDPGFX PDUs. The bug is     in gdi_CacheToSurface: it validates a destination rectangle that is clamped to UINT16_MAX, but then     performs the copy using the original cacheEntry->width/height. This can cause a large out-of-bounds heap     write and may lead to client crashes or code execution. This bug is reachable from a malicious RDP server,     but only when the client has RDPGFX enabled. This vulnerability is fixed in 3.26.0. (CVE-2026-44421)

    FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.26.0, FreeRDP's planar bitmap     decoder has an out-of-bounds heap write when decoding RLE planar data. In libfreerdp/codec/planar.c,     freerdp_bitmap_decompress_planar() validates the X destination coordinate nXDst against the caller-     provided destination stride (nDstStep) even when it is writing into the internal temp buffer pTempData. An     attacker can bypass the check with a large nDstStep and a large nXDst, causing     planar_decompress_plane_rle() to write past the end of pTempData. This vulnerability is fixed in 3.26.0.
    (CVE-2026-45700)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of freerdp installed on the remote host is prior to 2.11.7-1. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2026-3356 advisory.

    FreeRDP before 3.26.0 contains a heap-buffer-overflow vulnerability in gdi_CacheToSurface that allows     remote attackers to write out-of-bounds heap memory. The vulnerability occurs because rectangle validation     clamps coordinates to UINT16_MAX but performs copy operations using unclamped cache entry dimensions,     enabling malicious RDP servers to trigger large out-of-bounds writes and potentially achieve remote code     execution or client crash. (CVE-2026-40033)

    FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.26.0, a malicious RDP client     can trigger a heap-buffer-overflow write in FreeRDP's server-side clipboard (cliprdr) channel by sending a     CB_CLIP_CAPS PDU with a too-small capabilitySetLength. This can crash the server process (remote DoS) and     may be exploitable for code execution because it corrupts heap memory. This vulnerability is fixed in     3.26.0. (CVE-2026-44420)

    FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.26.0, a malicious RDP server     can trigger a heap-buffer-overflow write in the FreeRDP client by sending crafted RDPGFX PDUs. The bug is     in gdi_CacheToSurface: it validates a destination rectangle that is clamped to UINT16_MAX, but then     performs the copy using the original cacheEntry->width/height. This can cause a large out-of-bounds heap     write and may lead to client crashes or code execution. This bug is reachable from a malicious RDP server,     but only when the client has RDPGFX enabled. This vulnerability is fixed in 3.26.0. (CVE-2026-44421)

    FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.26.0, FreeRDP's planar bitmap     decoder has an out-of-bounds heap write when decoding RLE planar data. In libfreerdp/codec/planar.c,     freerdp_bitmap_decompress_planar() validates the X destination coordinate nXDst against the caller-     provided destination stride (nDstStep) even when it is writing into the internal temp buffer pTempData. An     attacker can bypass the check with a large nDstStep and a large nXDst, causing     planar_decompress_plane_rle() to write past the end of pTempData. This vulnerability is fixed in 3.26.0.
    (CVE-2026-45700)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.26.0, a malicious RDP server     can trigger a heap-buffer-overflow write in the FreeRDP client by sending crafted RDPGFX PDUs. The bug is     in gdi_CacheToSurface: it validates a destination rectangle that is clamped to UINT16_MAX, but then     performs the copy using the original cacheEntry->width/height. This can cause a large out-of-bounds heap     write and may lead to client crashes or code execution. This bug is reachable from a malicious RDP server,     but only when the client has RDPGFX enabled. This vulnerability is fixed in 3.26.0. (CVE-2026-44421)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
325482	RHEL 10 : freerdp (RHSA-2026:36203)	Nessus	Red Hat Local Security Checks	high
323073	SUSE SLES16: freerdp / freerdp-devel / freerdp-proxy / freerdp-proxy-plugins / etc (SUSE-SU-2026:22194-1)	Nessus	SuSE Local Security Checks	high
322051	Amazon Linux 2023 : freerdp, freerdp-devel, freerdp-libs (ALAS2023-2026-1822)	Nessus	Amazon Linux Local Security Checks	high
322013	Amazon Linux 2 : freerdp, --advisory ALAS2-2026-3356 (ALAS-2026-3356)	Nessus	Amazon Linux Local Security Checks	high
318022	Linux Distros Unpatched Vulnerability : CVE-2026-44421	Nessus	Misc.	high

Detections

Analytics

CVE-2026-44421

high

Tenable Plugins

high

high

high

high

high