LibVNC before commit 4a21bbd097ef7c44bb000c3bd0907f96a10e4ce7 contains null pointer dereference in VNC client code that can result DoS.
- Published
- Dec 19, 2018
- Updated
- Jun 16, 2026
- EPSS
- 3.3% · 88th percentile
- CWE
- CWE-476
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Report tools
Action score
31
Monitor
Low priority for now.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 3.3%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| libvnc project | libvncserver | cpe:2.3:a:libvnc_project:libvncserver |
| canonical | ubuntu linux | cpe:2.3:o:canonical:ubuntu_linux |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
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
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Kaspersky). Independent of NVD's CPE analysis and usually ahead of it.
n/a LibVNC
- commit 4a21bbd097ef7c44bb000c3bd0907f96a10e4ce7affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | libvncserver | before 0.9.11+dfsg-1.2 | 0.9.11+dfsg-1.2 |
| Debian:12 | ssvnc | before 1.0.29-5 | 1.0.29-5 |
| Debian:12 | veyon | before 4.1.4+repack1-1 | 4.1.4+repack1-1 |
| Debian:8 | italc | before 1:2.0.2+dfsg1-2+deb8u1 | 1:2.0.2+dfsg1-2+deb8u1 |
| Debian:8 | libvncserver | before 0.9.9+dfsg2-6.1+deb8u4 | 0.9.9+dfsg2-6.1+deb8u4 |
| Debian:8 | ssvnc | before 1.0.29-2+deb8u1 | 1.0.29-2+deb8u1 |
| Debian:9 | libvncserver | before 0.9.11+dfsg-1.3~deb9u1 | 0.9.11+dfsg-1.3~deb9u1 |
| openSUSE:Leap 15.0 | LibVNCServer | before 0.9.10-lp150.3.3.1 | 0.9.10-lp150.3.3.1 |
| SUSE:Linux Enterprise Module for Package Hub 15 | LibVNCServer | before 0.9.10-4.3.1 | 0.9.10-4.3.1 |
| SUSE:Linux Enterprise Software Development Kit 11 SP4 | LibVNCServer | before 0.9.1-160.6.1 | 0.9.1-160.6.1 |
| SUSE:OpenStack Cloud 7 | LibVNCServer | before 0.9.9-17.8.1 | 0.9.9-17.8.1 |
Same product
libvnc project: all recordsOther 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 transfer44Plan
- CVE-2018-15126LibVNC before commit 73cb96fec028a576a5a24417b57723b55854ad7b contains heap use-after-free vulnerability in server code of file transfer ext43Plan
- CVE-2018-20020LibVNC before commit 7b1ef0ffc4815cab9a96c7278394152bdc89dc4d contains heap out-of-bound write vulnerability inside structure in VNC client 42Plan
- CVE-2018-20019LibVNC before commit a83439b9fbe0f03c48eb94ed05729cb016f8b72f contains multiple heap out-of-bound write vulnerabilities in VNC client code t42Plan
- CVE-2019-20788libvncclient/cursor.c in LibVNCServer through 0.9.12 has a HandleCursorShape integer overflow and heap-based buffer overflow via a large hei40Plan
- CVE-2018-20750LibVNC through 0.9.12 contains a heap out-of-bounds write vulnerability in libvncserver/rfbserver.c.40Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:italc | 1:2.0.2+dfsg1-2+deb8u1 · Debian:8 | Package registry (OSV) |
| debian:libvncserver | 0.9.11+dfsg-1.2 · Debian:12 | Package registry (OSV) |
| debian:ssvnc | 1.0.29-5 · Debian:12 | Package registry (OSV) |
| debian:veyon | 4.1.4+repack1-1 · Debian:12 | Package registry (OSV) |
| opensuse:LibVNCServer | 0.9.10-lp150.3.3.1 · openSUSE:Leap 15.0 | Package registry (OSV) |
| suse:LibVNCServer | 0.9.9-17.8.1 · SUSE:OpenStack Cloud 7 | Package 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.
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.
No commit or PR link among the references.
Credits
All researchersFinders, 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
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-476 · NULL Pointer DereferenceCVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- ics-cert.kaspersky.com/advisories/klcert-advisories/2018/12/19/klcert-18-034-libvnc-null-pointer-dereference/
- lists.debian.org/debian-lts-announce/2018/12/msg00017.html
- lists.debian.org/debian-lts-announce/2019/10/msg00042.html
- lists.debian.org/debian-lts-announce/2019/11/msg00033.html
- security.gentoo.org/glsa/201908-05
- security.gentoo.org/glsa/202006-06
- usn.ubuntu.com/3877-1/
- usn.ubuntu.com/4547-1/
- usn.ubuntu.com/4547-2/
- usn.ubuntu.com/4587-1/
- www.debian.org/security/2019/dsa-4383
Vendor advisories and official records. Exploit/PoC links are deliberately left out.