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🛡️ CVE-2026-7828 — ultravnc

🟡 CVSS 5.3 — Medium ✅ No Known Exploit CWE-190 NVD
5.3
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability low.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: Low — limited, and the attacker does not choose what is affected.

Weakness class

CVE-2026-7828 is classified as CWE-190: Integer Overflow or Wraparound. Arithmetic produces a value too large for its type and wraps around, so a later size or bounds check passes when it should not.

Affected software

CVE-2026-7828 is recorded against 1 package.

  • ultravnc (fixed in 1.8.2.2)

Timeline and source

Published on 1 July 2026 and last revised on 9 July 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com
uvnc.com
www.securin.io

Other advisories for this package

ultravnc has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-190: Integer Overflow or Wraparound) in other software:

Details

Severity MEDIUM
CVSS Score 5.3
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CWE CWE-190
Public Exploit ✅ No
Source NVD
Published 2026-07-01
Updated 2026-08-20
Modified 2026-07-09
Fix URL N/A

Affected Packages

Software From version Fixed in
ultravnc — 1.8.2.2

Similar Threats

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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