CVE-2026-7831

highpriority · track · 0EPSS 0.007 · 54 %ileDEEUUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

0.74% (54th) EPSS

CVSS 7.5 · high

Is it mine?

4 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · cert_bund · nvd

EPSS · scored 2026-10-26

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 in its ServerInit message. On release builds without stack canaries the single-byte NUL overwrite adjacent stack data. On builds with /GS stack protection the canary is corrupted and the process terminates, resulting in denial of service. User interaction (connecting the viewer to the malicious server) is required.

cvss

Technical severity, 0–10. One row per scoring source.

7.6

010

base score 0–10 · higher = more severe · hover a vector to decode

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:Hsecondary · ENISA EU

v3.17.6highCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:Hsecondaryexploitability 2.8 · impact 4.7

v3.17highCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-193USCWE-787US

affected products (4)

Products and version ranges known to be affected.

UltraVNC UltraVNC <1.8.2.4all versionscert_bundDE
UltraVNC UltraVNC< 1.8.2.4cert_bundDE
Uvnc UltraVNC≤ 0 ≤1.8.2.2enisa_euvdEU
uvnc ultravnc≤ 1.8.2.2nvdUScpe:2.3:a:uvnc:ultravnc:*:*:*:*:*:*:*:*

advisories (1)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2026-2162UltraVNC: Mehrere SchwachstellenDeutsch2026-06-30csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in UltraVNC ausnutzen, um beliebigen Programmcode auszuführen, vertrauliche Informationen offenzulegen, Daten zu manipulieren, und einen Denial of Service zu verursachen.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd cert_bund nvd NVD CVE.org MITRE

published 2026-07-01modified 2026-10-25

references (9)

External citations — patches, advisories, analysis.

scry

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