LibVNC before 0.9.12 contains multiple heap out-of-bounds write vulnerabilities in libvncclient/rfbproto.c. The fix for CVE-2018-20019 was incomplete.
CVE-2018-20748
“—” beside the score: it is equal to NVD's CVSS score.
Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-13. NVD baseline CVSS 9.8; sources differ by 0.0.
Also known asEUVD-2018-13291 (ENISA EUVD) · GHSA-vvj8-j245-7346 (GitHub Security Advisories)Source: ENISA EUVD
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 9.8
- EG Score
- 9.8CRITICALmedium confidence
- EG Risk
- 45EG Risk 45/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity98% × 45%Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation3.3% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's BOD 26-04 default: no one has published Automatable for this CVE, and CISA treats it as “no” for a CVE not in KEV.SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- 3.3%
- EPSS %ILE
- 88th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 3.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
January 30, 2019
Last Modified
November 21, 2024
Advisory Details (8)
Auto-updated Oct 6, 2026[SECURITY] [DLA 1979-1] italc security update
https://lists.debian.org/debian-lts-announce/2019/10/msg00042.html[SECURITY] [DLA 1652-1] libvncserver security update
https://lists.debian.org/debian-lts-announce/2019/01/msg00029.htmlSECURITY: malloc((uint64_t)length + 1) is unsafe, especially on 32-bit systems · Issue #273 · LibVNC/libvncserver · GitHub
https://github.com/LibVNC/libvncserver/issues/273commit e34bcbb759ca (LibVNC/libvncserver)
Patch available: LibVNC/libvncserver LibVNCServer-0.9.12 (contains commit e34bcbb759ca)
https://github.com/LibVNC/libvncserver/commit/e34bcbb759ca5bef85809967a268fdf214c1ad2ccommit c5ba3fee85a7 (LibVNC/libvncserver)
Patch available: LibVNC/libvncserver LibVNCServer-0.9.12 (contains commit c5ba3fee85a7)
https://github.com/LibVNC/libvncserver/commit/c5ba3fee85a7ecbbca1df5ffd46d32b92757bc2acommit c2c4b81e6cb3 (LibVNC/libvncserver)
Patch available: LibVNC/libvncserver LibVNCServer-0.9.12 (contains commit c2c4b81e6cb3)
https://github.com/LibVNC/libvncserver/commit/c2c4b81e6cb3b485fb1ec7ba9e7defeb889f6ba7commit a64c3b37af9a (LibVNC/libvncserver)
Patch available: LibVNC/libvncserver LibVNCServer-0.9.12 (contains commit a64c3b37af9a)
https://github.com/LibVNC/libvncserver/commit/a64c3b37af9a6c8f8009d7516874b8d266b42baePatch Availability(3)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| ubuntu | libitalccore (1:3.0.3+dfsg1-3ubuntu0.1) @ bionic | 2026-11-02 | ubuntu |
| ubuntu | libitalccore (1:2.0.2+dfsg1-4ubuntu0.1) @ xenial | 2026-11-02 | ubuntu |
| ubuntu | libvncserver1 (0.9.11+dfsg-1.1ubuntu0.1) @ cosmic | 2026-11-02 | ubuntu |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(10 across 5 ecosystems)
Debian:11(2)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libvncserver | — |
| — |
| veyon | — |
| — |
Debian:12(2)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libvncserver | — |
| — |
| veyon | — |
| — |
Debian:13(2)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libvncserver | — |
| — |
| veyon | — |
| — |
Debian:14(2)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| libvncserver | — |
| — |
| veyon | — |
| — |
Debian:8(2)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| italc | 1:2.0.2+dfsg1-2 |
| — |
| libvncserver | 0.9.9+dfsg-6.1, 0.9.9+dfsg2-6.1+deb8u1, 0.9.9+dfsg2-6.1+deb8u2, 0.9.9+dfsg2-6.1+deb8u3, 0.9.9+dfsg2-6.1+deb8u4 |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
All Vendor Advisories
(3)
Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.
Data Freshness Timeline
(refreshed 24× in last 7d / 81× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
Showing the most recent 99 of 233 refreshes on record for this CVE.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 1 repeat row among the latest 100 is merged into the row it repeats. The 134 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-02 01:24 UTCEG score recompute
- 2026-11-02 01:24 UTCVendor advisory
- 2026-11-02 01:24 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-11-01 00:43 UTCEG score recompute
- 2026-11-01 00:43 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-31 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-31 00:01 UTCEG score recompute
- 2026-10-31 00:01 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-30 16:28 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-29 23:20 UTCEG score recompute
- 2026-10-29 23:20 UTCVendor advisory
- 2026-10-29 23:20 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-29 16:28 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-28 22:39 UTCEG score recompute
- 2026-10-28 22:39 UTCVendor advisory
- 2026-10-28 22:39 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-28 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-27 21:59 UTCEG score recompute
- 2026-10-27 21:59 UTCVendor advisory
- 2026-10-27 21:59 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-27 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-26 21:18 UTCEG score recompute
- 2026-10-26 21:18 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-26 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-25 18:30 UTCEG score recompute
Show 74 moreShow fewer
- 2026-10-25 18:30 UTCVendor advisory
- 2026-10-25 18:30 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-25 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-24 17:47 UTCEG score recompute
- 2026-10-24 17:47 UTCVendor advisory
- 2026-10-24 17:47 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-24 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-23 17:06 UTCEG score recompute
- 2026-10-23 17:06 UTCVendor advisory
- 2026-10-23 17:06 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-23 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-22 16:28 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-22 16:25 UTCEG score recompute
- 2026-10-22 16:25 UTCVendor advisory
- 2026-10-22 16:25 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-21 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-21 15:26 UTCEG score recompute
- 2026-10-21 15:26 UTCVendor advisory
- 2026-10-21 15:26 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-20 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-20 14:46 UTCEG score recompute
- 2026-10-20 14:45 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-19 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-19 13:56 UTCEG score recompute
- 2026-10-19 13:56 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-18 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-18 13:12 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-18 10:13 UTCEG score recompute
- 2026-10-17 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-17 12:30 UTCEG score recompute
- 2026-10-17 12:29 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-16 16:30 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-16 11:49 UTCEG score recompute
- 2026-10-16 11:49 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-15 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-15 11:07 UTCEG score recompute
- 2026-10-15 11:07 UTCVendor advisory
- 2026-10-15 11:07 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-14 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-14 06:53 UTCEG score recompute
- 2026-10-14 06:53 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-13 16:27 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-13 02:11 UTCGHSA enrichmentGHSA-vvj8-j245-7346 · GitHub severity CRITICAL · GitHub CVSS 9.8
- 2026-10-12 20:12 UTCEG score recompute
- 2026-10-12 16:28 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-12 00:36 UTCEG score recompute
- 2026-10-11 13:41 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-10 19:55 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-09 20:02 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-09 07:28 UTCOSV refresh
- 2026-10-08 16:36 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-07 23:42 UTCEPSS rescoreEPSS 3.3% · 88th percentile
- 2026-10-06 15:12 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-10-05 17:39 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-10-04 23:18 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-10-03 14:21 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-10-01 19:44 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-30 14:59 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-30 09:59 UTCEG score recompute
- 2026-09-28 13:45 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-27 13:40 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-26 15:53 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-24 13:59 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-20 20:10 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-19 15:36 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-19 14:33 UTCOSV refresh
- 2026-09-18 19:22 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-17 19:22 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-16 05:06 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-15 03:05 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-13 16:42 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-12 14:56 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-11 14:47 UTCEPSS rescoreEPSS 3.3% · 87th percentile
- 2026-09-11 09:32 UTCEPSS rescoreEPSS 3.3% · 87th percentile
Related CVEs(same product + same vendor + same CWE)
Same product
10 shownDebian:11:veyon · Debian:8:italc
Same vendor
10 shownubuntu:USN-3877-1 · ubuntu:USN-4547-1
Same CWE
10 shownCWE-787
Frequently asked(5)
What is CVE-2018-20748?
When was CVE-2018-20748 made public?
Is CVE-2018-20748 actively exploited?
What is the CVSS score of CVE-2018-20748?
How do I remediate CVE-2018-20748?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2018-20748
Is Your Infrastructure Affected by CVE-2018-20748?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.