166 lines
6.8 KiB
JSON
166 lines
6.8 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-44040",
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"assignerOrgId": "33c584b5-0579-4c06-b2a0-8d8329fcab9c",
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"state": "PUBLISHED",
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"assignerShortName": "securin",
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"dateReserved": "2026-05-05T03:40:37.003Z",
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"datePublished": "2026-07-01T03:33:20.355Z",
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"dateUpdated": "2026-07-09T04:36:05.643Z"
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},
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"containers": {
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"cna": {
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"title": "UltraVNC vncauth.c uses time-seeded libc rand() to generate VNC authentication challenge bytes",
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"descriptions": [
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{
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"lang": "en",
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"value": "UltraVNC through 1.8.2.2 uses a cryptographically weak pseudo-random number generator to produce VNC authentication challenge bytes. In rfb/vncauth.c:119-129, the vncRandomBytes() function seeds libc rand() with time(0) + getpid() + rand() and generates a 16-byte challenge. The combined seed space is approximately 31 bits (libc rand() internal state) and is entirely determined by publicly-observable values (wall-clock time and process ID). An attacker who can observe the authentication exchange can enumerate the seed space and predict the challenge within seconds, enabling forgery or offline brute-forcing of responses. Note: on Windows, the active code path may use vncEncryptBytes2.cpp which calls CryptGenRandom; reachability on shipped Windows binaries requires compile-graph verification and is under investigation."
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}
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],
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"affected": [
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{
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"vendor": "uvnc",
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"product": "UltraVNC",
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"versions": [
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{
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"version": "0",
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"lessThanOrEqual": "1.8.2.2",
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"status": "affected",
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"versionType": "custom"
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}
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],
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"defaultStatus": "unaffected",
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"modules": [
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"winvnc",
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"vncviewer"
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]
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}
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],
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"problemTypes": [
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{
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"descriptions": [
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{
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"type": "CWE",
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"cweId": "CWE-338",
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"lang": "en",
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"description": "Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)"
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}
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]
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}
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],
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"metrics": [
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{
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"format": "CVSS",
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"scenarios": [
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{
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"lang": "en",
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"value": "GENERAL"
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}
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],
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N",
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"attackVector": "NETWORK",
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"attackComplexity": "HIGH",
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"privilegesRequired": "NONE",
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"userInteraction": "NONE",
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"scope": "UNCHANGED",
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"confidentialityImpact": "LOW",
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"integrityImpact": "LOW",
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"availabilityImpact": "NONE",
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"baseScore": 4.8,
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"baseSeverity": "MEDIUM"
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}
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}
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],
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"references": [
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{
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"url": "https://uvnc.com/",
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"name": "UltraVNC project page",
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"tags": [
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"vendor-advisory"
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]
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},
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{
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"url": "https://github.com/ultravnc/UltraVNC",
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"name": "UltraVNC source repository",
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"tags": [
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"product"
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]
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},
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{
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"url": "https://www.securin.io/zero-days/cve-2026-44040-libc-rand-weak-rng-vnc-auth-challenge-ultravnc"
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}
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],
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"timeline": [
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{
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"time": "2026-06-02T00:00:00.000Z",
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"lang": "en",
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"value": "Vulnerability discovered during security audit"
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},
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{
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"time": "2026-06-17T00:00:00.000Z",
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"lang": "en",
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"value": "Reported to vendor (coordinated disclosure)"
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},
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{
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"time": "2026-09-15T00:00:00.000Z",
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"lang": "en",
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"value": "Planned public disclosure (90-day window)"
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}
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],
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"credits": [
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{
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"lang": "en",
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"value": "Arjun Basnet, Securin (arjun.basnet@securin.io)",
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"type": "finder"
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}
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],
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"source": {
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"discovery": "EXTERNAL",
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"advisory": "Securin Security Advisory — FINDING-001"
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},
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"providerMetadata": {
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"orgId": "33c584b5-0579-4c06-b2a0-8d8329fcab9c",
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"shortName": "securin",
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"dateUpdated": "2026-07-09T04:36:05.643Z"
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}
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},
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"adp": [
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{
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"metrics": [
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{
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"other": {
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"type": "ssvc",
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"content": {
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"timestamp": "2026-07-01T12:44:56.012420Z",
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"id": "CVE-2026-44040",
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"options": [
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{
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"Exploitation": "none"
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},
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{
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"Automatable": "no"
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},
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{
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"Technical Impact": "partial"
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}
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],
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"role": "CISA Coordinator",
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"version": "2.0.3"
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}
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}
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}
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],
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"title": "CISA ADP Vulnrichment",
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"providerMetadata": {
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"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"shortName": "CISA-ADP",
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"dateUpdated": "2026-07-01T12:45:04.706Z"
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}
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}
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]
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}
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} |