CVE-2026-7828
UltraVNC repeater integer overflow in win_log malloc leading to heap overflow
- Published
- Updated
- Reserved
- Assigned by
- securin
Description
UltraVNC repeater through 1.8.2.2 contains an integer overflow in the HTTP request logging path. In repeater/webgui/settings.c:336, the win_log() function allocates list nodes via malloc(sizeof(struct LIST) + strlen(line)), where line is derived from HTTP request URIs. If strlen(line) is sufficiently large, the addition overflows to a value smaller than sizeof(struct LIST), causing a heap allocation smaller than required. The subsequent strcpy of the full string into the undersized allocation produces a heap buffer overflow. In the current implementation this overflow is bounded by the HTTP receive buffer size (WI_RXBUFSIZE = 153600 bytes, well below SIZE_MAX on 32-bit builds), limiting practical exploitability to a partial heap write. A remote unauthenticated attacker can trigger the theoretical overflow path by sending a maximally-sized URI in an HTTP request to the repeater HTTP port.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| securinCNA (assigner) | 3.1 | Medium5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
| NVDNVD · Modified | 3.1 | Medium5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
- EPSS (exploitation in 30 days)
- 1.4% · top 28% of all CVEs (5 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.
Weakness
Affected products
References (3)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://trackcve.app/cve/CVE-2026-7828)Record last updated .