CVE-2026-50538

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Source
https://cve.org/CVERecord?id=CVE-2026-50538
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-50538.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2026-50538
Aliases
  • GHSA-v9pm-47h4-jcq8
Downstream
Related
Published
2026-08-21T21:03:58Z
Modified
2026-09-09T18:26:42Z
Severity
  • 8.8 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H CVSS Calculator
Summary
libvncclient Tight decoder has an attacker-controlled heap out-of-bounds write
Details

LibVNCClient is a library for easy implementation of a VNC client. In versions 0.9.12 through 0.9.15, a malicious (or man-in-the-middle) VNC server can force a connecting libvncclient to write attacker-controlled data past the end of its framebuffer. This is an out-of-bounds heap write with attacker-controlled length, contents, and offset. It needs no authentication (the attacker is the server), works in a default build with default settings, and fires from a single FramebufferUpdate the moment the victim connects. It crashes any client unconditionally (denial of service); we also demonstrated it overwriting an application callback pointer and redirecting execution to attacker-chosen code (code execution) under the default configuration. Commit 540332be3e0acc566fa64da6f1b4680c72c724dd patches the issue.

Database specific 
{
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-122",
        "CWE-787"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50538.json"
}
References

Affected packages

Git / github.com/libvnc/libvncserver

Affected ranges

Type
GIT
Repo
https://github.com/libvnc/libvncserver
Events
Introduced
0a70095271d845d16a3ed17354841b01f33963ad
Fixed
9b54b1ec32731bd23158ca014dc18014db4194c3
Fixed
540332be3e0acc566fa64da6f1b4680c72c724dd
Database specific
Show details 
{
    "extracted_events": [
        {
            "introduced": "0.9.12"
        },
        {
            "fixed": "0.9.15"
        }
    ],
    "source": [
        "DESCRIPTION",
        "REFERENCES"
    ]
}

Affected versions

LibVNCServer-0.*
LibVNCServer-0.9.12
LibVNCServer-0.9.13
LibVNCServer-0.9.14
LibVNCServer-0.9.15

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-50538.json"