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CVE-2018-20750· NVD / CVE Program· CNA mitre

LibVNC through 0.9.12 contains a heap out-of-bounds write vulnerability in libvncserver/rfbserver.c.

Noroxi assessment

Priority: Plan (action score 40/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 3.3% (FIRST EPSS); higher than 88.4% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: libvncserver (Debian:12) 0.9.11+dfsg-1.3; italc (Debian:8) 1:2.0.2+dfsg1-2+deb8u1; libvncserver (Debian:8) 0.9.9+dfsg2-6.1+deb8u5.

Add it to your regular patch cycle. Upgrade to libvncserver (Debian:12) 0.9.11+dfsg-1.3; italc (Debian:8) 1:2.0.2+dfsg1-2+deb8u1; libvncserver (Debian:8) 0.9.9+dfsg2-6.1+deb8u5 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

LibVNC through 0.9.12 contains a heap out-of-bounds write vulnerability in libvncserver/rfbserver.c. The fix for CVE-2018-15127 was incomplete.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Jan 30, 2019
Updated
Jun 16, 2026
EPSS
3.3% · 88th percentile

Report tools

JSON

Action score

40

Plan

Add it to your regular patch cycle.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 3.3%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
libvnc projectlibvncserver
canonicalubuntu linux
debiandebian linux
siemenssimatic itc1500 firmware
siemenssimatic itc1500
siemenssimatic itc1500 pro firmware
siemenssimatic itc1500 pro
siemenssimatic itc1900 firmware
siemenssimatic itc1900
siemenssimatic itc1900 pro firmware
siemenssimatic itc1900 pro
siemenssimatic itc2200 firmware

and 3 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • canonical ubuntu linux14.04
  • canonical ubuntu linux16.04
  • canonical ubuntu linux18.04
  • canonical ubuntu linux18.10
  • debian debian linux8.0
  • debian debian linux9.0
  • libvnc project libvncserverbefore 0.9.12
  • siemens simatic itc1500 firmware3.0.0.0 and later · before 3.2.1.0
  • siemens simatic itc1500 pro firmware3.0.0.0 and later · before 3.2.1.0
  • siemens simatic itc1900 firmware3.0.0.0 and later · before 3.2.1.0
  • siemens simatic itc1900 pro firmware3.0.0.0 and later · before 3.2.1.0
  • siemens simatic itc2200 firmware3.0.0.0 and later · before 3.2.1.0
  • siemens simatic itc2200 pro firmware3.0.0.0 and later · before 3.2.1.0

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12libvncserverbefore 0.9.11+dfsg-1.30.9.11+dfsg-1.3
Debian:8italcbefore 1:2.0.2+dfsg1-2+deb8u11:2.0.2+dfsg1-2+deb8u1
Debian:8libvncserverbefore 0.9.9+dfsg2-6.1+deb8u50.9.9+dfsg2-6.1+deb8u5
openSUSE:Leap 15.0LibVNCServerbefore 0.9.10-lp150.3.6.10.9.10-lp150.3.6.1
SUSE:Linux Enterprise Module for Package Hub 15LibVNCServerbefore 0.9.10-4.6.10.9.10-4.6.1
SUSE:Linux Enterprise Software Development Kit 11 SP4LibVNCServerbefore 0.9.1-160.9.10.9.1-160.9.1
SUSE:OpenStack Cloud 7LibVNCServerbefore 0.9.9-17.11.10.9.9-17.11.1

Same product

libvnc project: all records

Other highest-scoring records for the same primary product.

  • CVE-2018-15127LibVNC before commit 502821828ed00b4a2c4bef90683d0fd88ce495de contains heap out-of-bound write vulnerability in server code of file transfer
    44Plan
  • CVE-2018-15126LibVNC before commit 73cb96fec028a576a5a24417b57723b55854ad7b contains heap use-after-free vulnerability in server code of file transfer ext
    43Plan
  • CVE-2018-20020LibVNC before commit 7b1ef0ffc4815cab9a96c7278394152bdc89dc4d contains heap out-of-bound write vulnerability inside structure in VNC client
    42Plan

Published before and after this one in the same product

  • ← EarlierCVE-2018-20748Jan 30, 2019 · LibVNC before 0.9.12 contains multiple heap out-of-bounds write vulnerabilities in libvncclient/rfbproto.c.
    40Plan
  • ← EarlierCVE-2018-20749Jan 30, 2019 · LibVNC before 0.9.12 contains a heap out-of-bounds write vulnerability in libvncserver/rfbserver.c.
    40Plan
  • Later →CVE-2019-15681Oct 29, 2019 · LibVNC commit before d01e1bb4246323ba6fcee3b82ef1faa9b1dac82a contains a memory leak (CWE-655) in VNC server code, which allow an attacker t
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:italc1:2.0.2+dfsg1-2+deb8u1 · Debian:8Package registry (OSV)
debian:libvncserver0.9.11+dfsg-1.3 · Debian:12Package registry (OSV)
opensuse:LibVNCServer0.9.10-lp150.3.6.1 · openSUSE:Leap 15.0Package registry (OSV)
suse:LibVNCServer0.9.10-4.6.1 · SUSE:Linux Enterprise Module for Package Hub 15Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-787 · Out-of-bounds Write

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (8 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records