{"id":"CVE-2026-107611","state":"PUBLISHED","title":"Out-of-bounds read in TightVNC Viewer ZRLE palette decoding","description":"An out-of-bounds read vulnerability in the ZRLE decoder of GlavSoft TightVNC Viewer for Windows before 2.8.88 allows a malicious or compromised VNC server to read heap memory beyond the palette allocation and crash the viewer by sending ZRLE-encoded tiles whose palette indices exceed the declared palette size. readPaletteRleTile() and readPackedPaletteTile() use the attacker-supplied index to look up colours without validating it against the palette size; out-of-bounds heap data is copied into the framebuffer (garbled display) or the read faults, terminating the viewer.","publishedAt":"2026-10-08T13:39:48.883Z","updatedAt":"2026-10-08T14:03:01.404Z","severity":{"score":7.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H","source":"securin"},"assigner":"securin","products":["GlavSoft TightVNC"],"affected":[{"vendor":"GlavSoft","product":"TightVNC","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"2.8.88","versionType":"custom"}],"platforms":["Windows"],"modules":["TightVNC Viewer (ZRLE decoder)"],"programFiles":["ZrleDecoder.cpp"],"programRoutines":[{"name":"readPaletteRleTile()"},{"name":"readPackedPaletteTile()"}]}],"references":["https://sourceforge.net/p/vnc-tight/bugs/1657/","https://www.tightvnc.com/whatsnew.php"],"weaknesses":["CWE-125"],"ingestedAt":"2026-10-29T20:10:23.711Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/107xxx/CVE-2026-107611.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-107611","state":"PUBLISHED","datePublished":"2026-10-08T13:39:48.883Z","dateUpdated":"2026-10-08T14:03:01.404Z","assignerShortName":"securin","assignerOrgId":"33c584b5-0579-4c06-b2a0-8d8329fcab9c","dateReserved":"2026-10-08T13:23:07.677Z"},"containers":{"cna":{"title":"Out-of-bounds read in TightVNC Viewer ZRLE palette decoding","descriptions":[{"lang":"en","value":"An out-of-bounds read vulnerability in the ZRLE decoder of GlavSoft TightVNC Viewer for Windows before 2.8.88 allows a malicious or compromised VNC server to read heap memory beyond the palette allocation and crash the viewer by sending ZRLE-encoded tiles whose palette indices exceed the declared palette size. readPaletteRleTile() and readPackedPaletteTile() use the attacker-supplied index to look up colours without validating it against the palette size; out-of-bounds heap data is copied into the framebuffer (garbled display) or the read faults, terminating the viewer."}],"affected":[{"vendor":"GlavSoft","product":"TightVNC","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"2.8.88","versionType":"custom"}],"platforms":["Windows"],"modules":["TightVNC Viewer (ZRLE decoder)"],"programFiles":["ZrleDecoder.cpp"],"programRoutines":[{"name":"readPaletteRleTile()"},{"name":"readPackedPaletteTile()"}]}],"references":[{"url":"https://sourceforge.net/p/vnc-tight/bugs/1657/","name":"TightVNC bug #1657","tags":["issue-tracking"]},{"url":"https://www.tightvnc.com/whatsnew.php","name":"TightVNC release notes (2.8.88)","tags":["release-notes","patch"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H","baseScore":7.1,"baseSeverity":"HIGH"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-125","lang":"en","type":"CWE","description":"CWE-125 Out-of-bounds Read"}]}],"providerMetadata":{"shortName":"securin","orgId":"33c584b5-0579-4c06-b2a0-8d8329fcab9c","dateUpdated":"2026-10-08T13:39:48.883Z"},"solutions":[{"lang":"en","value":"Upgrade TightVNC for Windows to version 2.8.88 or later."}],"credits":[{"lang":"en","type":"finder","value":"Arjun Basnet from Securin"}],"timeline":[{"time":"2026-05-30T00:00:00.000Z","lang":"en","value":"Reported to GlavSoft"},{"time":"2026-06-02T00:00:00.000Z","lang":"en","value":"Vendor acknowledged"},{"time":"2026-06-19T00:00:00.000Z","lang":"en","value":"TightVNC 2.8.88 released with fix"}],"source":{"discovery":"EXTERNAL"},"impacts":[{"capecId":"CAPEC-540","descriptions":[{"lang":"en","value":"CAPEC-540 Overread Buffers"}]}],"workarounds":[{"lang":"en","value":"Connect only to trusted VNC servers until the viewer is upgraded."}]},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-08T14:02:42.563819Z","id":"CVE-2026-107611","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-08T14:03:01.404Z"}}]}}}