{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-107611", "assignerOrgId": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "state": "PUBLISHED", "assignerShortName": "securin", "dateReserved": "2026-10-08T13:23:07.677Z", "datePublished": "2026-10-08T13:39:48.883Z", "dateUpdated": "2026-10-08T14:03:01.404Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "33c584b5-0579-4c06-b2a0-8d8329fcab9c", "shortName": "securin", "dateUpdated": "2026-10-08T13:39:48.883Z"}, "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", "platforms": ["Windows"], "modules": ["TightVNC Viewer (ZRLE decoder)"], "programFiles": ["ZrleDecoder.cpp"], "programRoutines": [{"name": "readPaletteRleTile()"}, {"name": "readPackedPaletteTile()"}], "defaultStatus": "unaffected", "versions": [{"version": "0", "lessThan": "2.8.88", "status": "affected", "versionType": "custom"}]}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-125", "description": "CWE-125 Out-of-bounds Read"}]}], "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"}}], "solutions": [{"lang": "en", "value": "Upgrade TightVNC for Windows to version 2.8.88 or later."}], "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"]}], "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": [{"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"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-08T14:03:01.404Z"}}]}}

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