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CVE-2026-7831

UltraVNC viewer through 1.8.2.2 contains an off-by-one stack buffer overflow in the RFB ServerInit message handler. In vncviewer/ClientConnection.cpp, when the server-supplied nameLength equals exactly 2024 the code declares a 2024-byte stack buffer _dn[2024] and calls ReadString(_dn, 2024). ReadString writes the NUL terminator at buf[length], i.e., _dn[2024], one byte past the end of the stack buffer. A malicious VNC server can trigger this condition by advertising a desktop name of length 2024
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:70c332daed5f0abac0a120b45bad80d75e4027a0c6cf76a81072e4541943467f
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
1

Preserved source conflicts

No provider value was silently selected as the winner.

cwe · 2 assertions

{"cweId":"CWE-787","description":"Out-of-bounds Write","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:60b0d08987a0cdf0f04e042c3e5c585d61324007ee77e05bb7077c0b80d1882b · sha256:238e52a377b584c3… · /containers/cna/problemTypes/1/descriptions/0

{"cweId":"CWE-193","description":"Off-by-one Error","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:60b0d08987a0cdf0f04e042c3e5c585d61324007ee77e05bb7077c0b80d1882b · sha256:238e52a377b584c3… · /containers/cna/problemTypes/0/descriptions/0

Affected products and versions

1 source assertion
{"defaultStatus":"unaffected","modules":["vncviewer"],"product":"UltraVNC","vendor":"uvnc","versions":[{"lessThanOrEqual":"1.8.2.2","status":"affected","version":"0","versionType":"custom"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:60b0d08987a0cdf0f04e042c3e5c585d61324007ee77e05bb7077c0b80d1882b · sha256:238e52a377b584c3… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion
{"metric":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H","version":"3.1"},"metric_type":"cvssV3_1"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:60b0d08987a0cdf0f04e042c3e5c585d61324007ee77e05bb7077c0b80d1882b · sha256:238e52a377b584c3… · /containers/cna/metrics/0/cvssV3_1

CWE assertions

2 source assertions
{"cweId":"CWE-787","description":"Out-of-bounds Write","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:60b0d08987a0cdf0f04e042c3e5c585d61324007ee77e05bb7077c0b80d1882b · sha256:238e52a377b584c3… · /containers/cna/problemTypes/1/descriptions/0
{"cweId":"CWE-193","description":"Off-by-one Error","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:60b0d08987a0cdf0f04e042c3e5c585d61324007ee77e05bb7077c0b80d1882b · sha256:238e52a377b584c3… · /containers/cna/problemTypes/0/descriptions/0

Source references

3 source assertions
{"name":"UltraVNC source repository","tags":["product"],"url":"https://github.com/ultravnc/UltraVNC"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:60b0d08987a0cdf0f04e042c3e5c585d61324007ee77e05bb7077c0b80d1882b · sha256:238e52a377b584c3… · /containers/cna/references/1
{"name":"UltraVNC project page","tags":["vendor-advisory"],"url":"https://uvnc.com/"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:60b0d08987a0cdf0f04e042c3e5c585d61324007ee77e05bb7077c0b80d1882b · sha256:238e52a377b584c3… · /containers/cna/references/0
{"url":"https://www.securin.io/zero-days/cve-2026-7831-off-by-one-stack-overflow-viewer-namelength-ultravnc"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:60b0d08987a0cdf0f04e042c3e5c585d61324007ee77e05bb7077c0b80d1882b · sha256:238e52a377b584c3… · /containers/cna/references/2

Attribution and limitations

  • CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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