CVE-2018-20748

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-13. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 3%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
50(Track)
EG Risk 50/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation3% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
86.9%
KEV
Not listed

Published

January 30, 2019

Last Modified

November 21, 2024

Advisory Details (7)

Auto-updated Jun 7, 2026
Patch available. Sources: github_commit.
generic Patch Available

[SECURITY] [DLA 1979-1] italc security update

https://lists.debian.org/debian-lts-announce/2019/10/msg00042.html
generic Patch Available

[SECURITY] [DLA 1652-1] libvncserver security update

https://lists.debian.org/debian-lts-announce/2019/01/msg00029.html
generic

SECURITY: malloc((uint64_t)length + 1) is unsafe, especially on 32-bit systems · Issue #273 · LibVNC/libvncserver · GitHub

https://github.com/LibVNC/libvncserver/issues/273
github_commit Patch Available

commit e34bcbb759ca (LibVNC/libvncserver)

Patch available: LibVNC/libvncserver LibVNCServer-0.9.12 (contains commit e34bcbb759ca)

https://github.com/LibVNC/libvncserver/commit/e34bcbb759ca5bef85809967a268fdf214c1ad2c
github_commit Patch Available

commit c5ba3fee85a7 (LibVNC/libvncserver)

Patch available: LibVNC/libvncserver LibVNCServer-0.9.12 (contains commit c5ba3fee85a7)

https://github.com/LibVNC/libvncserver/commit/c5ba3fee85a7ecbbca1df5ffd46d32b92757bc2a
github_commit Patch Available

commit c2c4b81e6cb3 (LibVNC/libvncserver)

Patch available: LibVNC/libvncserver LibVNCServer-0.9.12 (contains commit c2c4b81e6cb3)

https://github.com/LibVNC/libvncserver/commit/c2c4b81e6cb3b485fb1ec7ba9e7defeb889f6ba7
github_commit Patch Available

commit a64c3b37af9a (LibVNC/libvncserver)

Patch available: LibVNC/libvncserver LibVNCServer-0.9.12 (contains commit a64c3b37af9a)

https://github.com/LibVNC/libvncserver/commit/a64c3b37af9a6c8f8009d7516874b8d266b42bae

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibvncserver1 (0.9.10+dfsg-3ubuntu0.16.04.3) @ xenial2026-05-23ubuntu
ubuntulibitalccore (1:2.0.2+dfsg1-4ubuntu0.1) @ xenial2026-05-23ubuntu
ubuntulibitalccore (1:3.0.3+dfsg1-3ubuntu0.1) @ bionic2026-05-23ubuntu

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.

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 10× in last 7d / 43× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-07-23 14:15 UTCEPSS rescore
  2. 2026-07-23 01:35 UTCEG score recompute
  3. 2026-07-22 22:15 UTCEG score recompute
  4. 2026-07-22 14:05 UTCEPSS rescore
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  17. 2026-07-12 19:38 UTCOSV refresh
  18. 2026-07-12 05:43 UTCEPSS rescore
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  20. 2026-07-09 19:06 UTCEPSS rescore
  21. 2026-07-08 15:11 UTCEPSS rescore
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  1. 2026-07-06 02:20 UTCEPSS rescore
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  5. 2026-07-02 16:54 UTCEPSS rescore
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  8. 2026-06-30 23:20 UTCEPSS rescore
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  17. 2026-06-24 14:02 UTCEPSS rescore
  18. 2026-06-24 14:02 UTCEPSS rescore
  19. 2026-06-24 04:59 UTCOSV refresh
  20. 2026-06-23 21:30 UTCEPSS rescore
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  22. 2026-06-23 21:30 UTCEPSS rescore
  23. 2026-06-22 14:23 UTCEPSS rescore
  24. 2026-06-21 14:54 UTCEPSS rescore
  25. 2026-06-21 14:54 UTCEPSS rescore
  26. 2026-06-21 01:57 UTCEPSS rescore
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  28. 2026-06-19 19:23 UTCEPSS rescore
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  30. 2026-06-18 17:50 UTCEPSS rescore
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  37. 2026-06-13 22:58 UTCEPSS rescore
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  40. 2026-06-11 13:57 UTCEPSS rescore
  41. 2026-06-10 22:16 UTCEPSS rescore
  42. 2026-06-10 13:19 UTCEPSS rescore
  43. 2026-06-07 15:22 UTCEPSS rescore
  44. 2026-06-07 15:22 UTCEPSS rescore
  45. 2026-06-07 09:30 UTCOSV refresh
  46. 2026-06-06 13:45 UTCEPSS rescore
  47. 2026-06-06 13:45 UTCEPSS rescore
  48. 2026-06-05 22:45 UTCEPSS rescore
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  63. 2026-05-27 13:38 UTCEPSS rescore
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  67. 2026-05-23 02:48 UTCEG score recompute
  68. 2026-05-23 02:48 UTCVendor advisory
  69. 2026-05-23 02:48 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2018-20748?
CVE-2018-20748 is a critical vulnerability published on January 30, 2019. 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.
When was CVE-2018-20748 disclosed?
CVE-2018-20748 was first published in the National Vulnerability Database on January 30, 2019, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2018-20748 actively exploited?
CVE-2018-20748 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 86.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2018-20748?
CVE-2018-20748 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2018-20748?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2018-20748, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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