{"id":"CVE-2026-44988","aliases":["DEBIAN-CVE-2026-44988","EUVD-2026-32525","GHSA-jcc5-8wj4-7c58","MGASA-2026-0315","OESA-2026-2490","OESA-2026-2491","OESA-2026-2564","OESA-2026-2565","SUSE-SU-2026:22190-1","SUSE-SU-2026:2227-1","SUSE-SU-2026:2427-1","SUSE-SU-2026:2428-1","UBUNTU-CVE-2026-44988","USN-8463-1","openSUSE-SU-2026:10905-1","openSUSE-SU-2026:21118-1"],"status":"published","title":"LibVNCClient Tight Gradient decoding allows malicious server-triggered heap/stack OOB writes","description":"LibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient's Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.","severity":{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00242,"percentile":0.15449,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-787"],"published":"2026-05-27T14:26:50Z","modified":"2026-10-28T10:55:34Z","fixes":[{"ecosystem":"Debian:12","package":"libvncserver","fixed_in":["0.9.14+dfsg-1+deb12u2"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"libvncserver","fixed_in":["0.9.15+dfsg-1+deb13u2"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"libvncserver","fixed_in":["0.9.15+dfsg-5"],"sources":["osv"]},{"ecosystem":"openEuler:24.03-LTS-SP1","package":"libvncserver","fixed_in":["0.9.13-5.oe2403sp1"],"sources":["osv"]},{"ecosystem":"openEuler:24.03-LTS","package":"libvncserver","fixed_in":["0.9.13-5.oe2403"],"sources":["osv"]},{"ecosystem":"openEuler:24.03-LTS-SP3","package":"libvncserver","fixed_in":["0.9.13-5.oe2403sp3"],"sources":["osv"]},{"ecosystem":"openEuler:22.03-LTS-SP4","package":"libvncserver","fixed_in":["0.9.13-5.oe2203sp4"],"sources":["osv"]},{"ecosystem":"SUSE:Linux 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Tight Gradient decoding allows malicious server-triggered heap/stack OOB writes","description":"LibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient's Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.","status":"published","published":"2026-05-27T14:26:50.063Z","modified":"2026-05-29T15:16:13.607Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-787"],"updated_at":"2026-11-02T13:43:00.288193Z"}],"euvd":[{"id":"EUVD-2026-32525","description":"LibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient's Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.","status":"published","published":"2026-05-27T14:26:50Z","modified":"2026-05-29T15:16:13Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high"}],"updated_at":"2026-11-02T18:21:00.772434Z"}],"nvd":[{"id":"CVE-2026-44988","description":"LibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient's Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.","status":"published","published":"2026-05-27T15:16:29.83Z","modified":"2026-10-26T11:10:00.157Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-787"],"updated_at":"2026-11-02T14:12:20.885865Z"}],"osv":[{"id":"CVE-2026-44988","title":"LibVNCClient Tight Gradient decoding allows malicious server-triggered heap/stack OOB writes","description":"LibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient's Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.","status":"published","published":"2026-05-27T14:26:50.063Z","modified":"2026-10-28T10:55:34.802841597Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high"}],"cwes":["CWE-787"],"updated_at":"2026-11-02T15:45:05.172514Z"},{"id":"DEBIAN-CVE-2026-44988","description":"LibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient's Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.","status":"published","published":"2026-05-27T15:16:29.83Z","modified":"2026-10-27T09:47:35.466008913Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high"}],"updated_at":"2026-11-02T15:45:55.669088Z"},{"id":"OESA-2026-2490","title":"libvncserver security update","description":"libvncserver is a set of programs using the RFB (Remote Frame Buffer) protocol. They are designed to \u0026amp;quot;export\u0026amp;quot; a frame buffer via net: you set up a server and can connect to it via VNC viewers. If the server supports WebSockets (which LibVNCServer does), you can also connect using an in-browser VNC viewer like noVNC. It is already in wide use for administration, but it is not that easy to program a server yourself.\r\n\r\nSecurity Fix(es):\n\nLibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient\u0026apos;s Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.(CVE-2026-44988)","status":"published","published":"2026-05-29T11:11:26Z","modified":"2026-08-18T01:20:01.061026091Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high"}],"updated_at":"2026-11-02T15:52:46.449097Z"},{"id":"OESA-2026-2491","title":"libvncserver security update","description":"libvncserver is a set of programs using the RFB (Remote Frame Buffer) protocol. They are designed to \u0026amp;quot;export\u0026amp;quot; a frame buffer via net: you set up a server and can connect to it via VNC viewers. If the server supports WebSockets (which LibVNCServer does), you can also connect using an in-browser VNC viewer like noVNC. It is already in wide use for administration, but it is not that easy to program a server yourself.\r\n\r\nSecurity Fix(es):\n\nLibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient\u0026apos;s Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.(CVE-2026-44988)","status":"published","published":"2026-05-29T11:11:26Z","modified":"2026-08-18T01:20:01.011776268Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high"}],"updated_at":"2026-11-02T15:52:46.449097Z"},{"id":"OESA-2026-2564","title":"libvncserver security update","description":"libvncserver is a set of programs using the RFB (Remote Frame Buffer) protocol. They are designed to \u0026amp;quot;export\u0026amp;quot; a frame buffer via net: you set up a server and can connect to it via VNC viewers. If the server supports WebSockets (which LibVNCServer does), you can also connect using an in-browser VNC viewer like noVNC. It is already in wide use for administration, but it is not that easy to program a server yourself.\r\n\r\nSecurity Fix(es):\n\nLibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient\u0026apos;s Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.(CVE-2026-44988)","status":"published","published":"2026-06-05T11:11:30Z","modified":"2026-08-18T01:20:02.769461536Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high"}],"updated_at":"2026-11-02T15:52:46.449097Z"},{"id":"OESA-2026-2565","title":"libvncserver security update","description":"libvncserver is a set of programs using the RFB (Remote Frame Buffer) protocol. They are designed to \u0026amp;quot;export\u0026amp;quot; a frame buffer via net: you set up a server and can connect to it via VNC viewers. If the server supports WebSockets (which LibVNCServer does), you can also connect using an in-browser VNC viewer like noVNC. It is already in wide use for administration, but it is not that easy to program a server yourself.\r\n\r\nSecurity Fix(es):\n\nLibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient\u0026apos;s Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.(CVE-2026-44988)","status":"published","published":"2026-06-05T11:11:30Z","modified":"2026-08-18T01:20:02.095106224Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high"}],"updated_at":"2026-11-02T15:52:46.449097Z"},{"id":"UBUNTU-CVE-2026-44988","description":"LibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient's Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.","status":"published","published":"2026-05-27T15:16:00Z","modified":"2026-10-17T12:58:22.00694447Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","level":"high"}],"updated_at":"2026-11-02T16:56:26.396868Z"},{"id":"MGASA-2026-0315","title":"Updated libvncserver packages fix security vulnerabilities","description":"The updated packages fix security vulnerabilities:\nHeap Out-of-Bounds Read in HandleUltraZipBPP due to unchecked\nsubrectangle count. (CVE-2026-32853)\nNULL pointer dereferences in httpd proxy handlers via malformed\nCONNECT/GET requests. (CVE-2026-32854)\nLibVNCClient Tight Gradient decoding allows malicious server-triggered\nheap/stack OOB writes. (CVE-2026-44988)\nAttacker-controlled heap out-of-bounds write in libvncclient Tight\ndecoder. (CVE-2026-50538)\n","status":"published","published":"2026-08-03T18:47:23Z","modified":"2026-08-03T19:00:05.507881509Z","updated_at":"2026-11-02T15:49:43.795591Z"},{"id":"openSUSE-SU-2026:10905-1","title":"LibVNCServer-devel-0.9.15-3.1 on GA media","description":"These are all security issues fixed in the LibVNCServer-devel-0.9.15-3.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-05-30T00:00:00Z","modified":"2026-05-31T14:15:04.993475074Z","updated_at":"2026-11-02T16:58:38.95195Z"},{"id":"openSUSE-SU-2026:21118-1","title":"Security update for LibVNCServer","description":"This update for LibVNCServer fixes the following issue\n\n- CVE-2026-44988: missing validation of rectangle width in tight gradient decoding can lead to server-triggered out-of-\n  bounds write (bsc#1266459).\n","status":"published","published":"2026-06-20T06:50:30Z","modified":"2026-06-30T18:24:42.649388162Z","updated_at":"2026-11-02T16:58:41.885092Z"},{"id":"SUSE-SU-2026:22190-1","title":"Security update for LibVNCServer","description":"This update for LibVNCServer fixes the following issue\n\n- CVE-2026-44988: missing validation of rectangle width in tight gradient decoding can lead to server-triggered out-of-\n  bounds write (bsc#1266459).\n","status":"published","published":"2026-06-20T06:50:27Z","modified":"2026-06-24T09:00:06.637364742Z","updated_at":"2026-11-02T15:54:02.654057Z"},{"id":"SUSE-SU-2026:2227-1","title":"Security update for LibVNCServer","description":"This update for LibVNCServer fixes the following issues:\n\n- CVE-2026-44988: Fixed missing validation of rectangle width in tight gradient\n  decoding can lead to server-triggered out-of-bounds write (bsc#1266459).\n","status":"published","published":"2026-06-03T08:06:47Z","modified":"2026-06-05T18:24:09.120366385Z","updated_at":"2026-11-02T15:54:02.654057Z"},{"id":"SUSE-SU-2026:2427-1","title":"Security update for LibVNCServer","description":"This update for LibVNCServer fixes the following issues:\n\n- CVE-2026-44988: Fixed missing validation of rectangle width in tight gradient\n  decoding can lead to server-triggered out-of-bounds write (bsc#1266459).\n","status":"published","published":"2026-06-17T09:50:22Z","modified":"2026-06-18T08:15:04.324367229Z","updated_at":"2026-11-02T15:54:04.519245Z"},{"id":"SUSE-SU-2026:2428-1","title":"Security update for LibVNCServer","description":"This update for LibVNCServer fixes the following issues:\n\n- CVE-2026-44988: Fixed missing validation of rectangle width in tight gradient\n  decoding can lead to server-triggered out-of-bounds write (bsc#1266459).\n","status":"published","published":"2026-06-17T09:50:32Z","modified":"2026-06-18T08:15:04.314306506Z","updated_at":"2026-11-02T15:54:04.519245Z"},{"id":"USN-8463-1","title":"libvncserver vulnerabilities","description":"It was discovered that LibVNCServer had a memory leak in the client cleanup\nfunction. An attacker could possibly use this issue to cause LibVNCServer\nto consume memory, leading to a denial of service. This issue only affected\nUbuntu 22.04 LTS. (CVE-2020-29260)\n\nIt was discovered that LibVNCServer did not properly validate bounds when\nhandling UltraZip encoding subrectangles. A remote attacker could possibly\nuse this issue to obtain sensitive information or cause a denial of\nservice. This issue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and\nUbuntu 25.04. (CVE-2026-32853)\n\nIt was discovered that LibVNCServer did not properly validate return values\nin the HTTP proxy handlers. A remote attacker could possibly use this issue\nto cause LibVNCServer to crash, resulting in a denial of service. This\nissue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 25.04.\n(CVE-2026-32854)\n\nIt was discovered that LibVNCServer did not properly handle Tight encoding\ngradient filter rectangles. A remote attacker could use this issue to cause\nLibVNCServer to crash, resulting in a denial of service, or possibly\nexecute arbitrary code. (CVE-2026-44988)","status":"published","published":"2026-06-23T14:46:54Z","modified":"2026-06-23T22:14:21.491003071Z","updated_at":"2026-11-02T16:58:25.103481Z"}]}}