CVE-2018-18955

HIGHNVD 7.07.0—
EchelonGraph scoreMEDIUM confidence

Score 7.0 from GitHub Security Advisory (severity: HIGH) published 2022-05-13. NVD baseline CVSS 7.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this weekWeaponized
7.0
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 8%CVSS: 7.0Exploit: NoneExposed: 0

A fix is available — apply it.

In the Linux kernel 4.15.x through 4.19.x before 4.19.2, map_write() in kernel/user_namespace.c allows privilege escalation because it mishandles nested user namespaces with more than 5 UID or GID ranges. A user who has CAP_SYS_ADMIN in an affected user namespace can bypass access controls on resources outside the namespace, as demonstrated by reading /etc/shadow. This occurs because an ID transformation takes place properly for the namespaced-to-kernel direction but not for the kernel-to-namespaced direction.

CVSS v3
7.0
EG Score
7.0(medium)
EG Risk
62(Track)
EG Risk 62/100SSVC: 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
Severity70% × 45%
Exploitation65% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
93.9%
KEV
Not listed

Published

November 16, 2018

Last Modified

November 21, 2024

References (30)

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-image-unsigned-4.15.0-42-lowlatency (4.15.0-42.45) @ bionic2026-05-28ubuntu
ubuntulinux-image-raspi2 (4.18.0.1007.4) @ cosmic2026-05-28ubuntu
ubuntulinux-image-unsigned-4.15.0-42-lowlatency (4.15.0-42.45~16.04.1) @ xenial2026-05-28ubuntu
ubuntulinux-image-4.15.0-1029-aws (4.15.0-1029.30) @ bionic2026-05-28ubuntu
ubuntulinux-image-4.18.0-1006-aws (4.18.0-1006.7) @ cosmic2026-05-28ubuntu

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

(5)

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 12× in last 7d / 49× 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 01:34 UTCEG score recompute
  2. 2026-07-22 22:15 UTCEG score recompute
  3. 2026-07-22 14:05 UTCEPSS rescore
  4. 2026-07-21 15:22 UTCEPSS rescore
  5. 2026-07-21 02:47 UTCOSV refresh
  6. 2026-07-20 17:04 UTCEPSS rescore
  7. 2026-07-20 17:04 UTCEPSS rescore
  8. 2026-07-19 14:28 UTCEPSS rescore
  9. 2026-07-19 02:26 UTCEPSS rescore
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  11. 2026-07-16 16:59 UTCEPSS rescore
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  20. 2026-07-12 05:43 UTCEPSS rescore
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  22. 2026-07-09 19:06 UTCEPSS rescore
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  24. 2026-07-07 13:42 UTCEPSS rescore
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Show 73 more
  1. 2026-07-06 16:24 UTCEPSS rescore
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  3. 2026-07-06 02:20 UTCEPSS rescore
  4. 2026-07-05 02:27 UTCEPSS rescore
  5. 2026-07-04 06:28 UTCEPSS rescore
  6. 2026-07-04 06:28 UTCEPSS rescore
  7. 2026-07-03 21:56 UTCOSV refresh
  8. 2026-07-02 16:54 UTCEPSS rescore
  9. 2026-07-01 15:03 UTCEPSS rescore
  10. 2026-07-01 15:03 UTCEPSS rescore
  11. 2026-06-30 23:20 UTCEPSS rescore
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  13. 2026-06-29 14:03 UTCEPSS rescore
  14. 2026-06-28 04:53 UTCEPSS rescore
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  16. 2026-06-27 03:06 UTCEPSS rescore
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  18. 2026-06-25 13:47 UTCEPSS rescore
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  20. 2026-06-24 14:02 UTCEPSS rescore
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  22. 2026-06-23 21:30 UTCEPSS rescore
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  24. 2026-06-23 21:30 UTCEPSS rescore
  25. 2026-06-22 14:23 UTCEPSS rescore
  26. 2026-06-21 01:57 UTCEPSS rescore
  27. 2026-06-21 01:57 UTCEPSS rescore
  28. 2026-06-19 19:23 UTCEPSS rescore
  29. 2026-06-19 19:23 UTCEPSS rescore
  30. 2026-06-18 17:50 UTCEPSS rescore
  31. 2026-06-18 17:50 UTCEPSS rescore
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  36. 2026-06-15 17:45 UTCEPSS rescore
  37. 2026-06-15 10:13 UTCOSV refresh
  38. 2026-06-14 23:15 UTCEPSS rescore
  39. 2026-06-14 23:14 UTCEPSS rescore
  40. 2026-06-13 22:58 UTCEPSS rescore
  41. 2026-06-12 23:09 UTCEPSS rescore
  42. 2026-06-12 23:09 UTCEPSS rescore
  43. 2026-06-11 13:57 UTCEPSS rescore
  44. 2026-06-10 22:16 UTCEPSS rescore
  45. 2026-06-10 13:19 UTCEPSS rescore
  46. 2026-06-08 14:14 UTCEPSS rescore
  47. 2026-06-08 14:14 UTCEPSS rescore
  48. 2026-06-07 15:22 UTCEPSS rescore
  49. 2026-06-07 15:22 UTCEPSS rescore
  50. 2026-06-06 13:45 UTCEPSS rescore
  51. 2026-06-06 13:45 UTCEPSS rescore
  52. 2026-06-05 22:45 UTCEPSS rescore
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  54. 2026-06-05 06:08 UTCEPSS rescore
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  56. 2026-06-04 13:10 UTCEPSS rescore
  57. 2026-06-02 20:11 UTCEPSS rescore
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  59. 2026-05-31 22:29 UTCEPSS rescore
  60. 2026-05-31 00:14 UTCEPSS rescore
  61. 2026-05-31 00:14 UTCEPSS rescore
  62. 2026-05-29 13:41 UTCEPSS rescore
  63. 2026-05-28 13:42 UTCEPSS rescore
  64. 2026-05-28 13:42 UTCEPSS rescore
  65. 2026-05-28 01:01 UTCEG score recompute
  66. 2026-05-28 01:01 UTCVendor advisory
  67. 2026-05-28 01:01 UTCGHSA enrichment
  68. 2026-05-27 13:38 UTCEPSS rescore
  69. 2026-05-27 13:38 UTCEPSS rescore
  70. 2026-05-26 13:42 UTCEPSS rescore
  71. 2026-05-26 13:42 UTCEPSS rescore
  72. 2026-05-26 07:17 UTCEPSS rescore
  73. 2026-05-26 07:17 UTCEPSS rescore

Publicly available exploits

(8 references)

Working exploit code is in the public domain (1 Metasploit module) (1 GitHub PoC) (6 Exploit-DB entries). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCscheatkode/CVE-2018-18955
    First seen Jan 19, 2022

    💀 Linux local root exploit for CVE-2018-18955

    Open source ↗
  • Exploit-DBEDB-47165
    First seen Jan 4, 2019

    Linux Kernel 4.15.x < 4.19.2 - 'map_write() CAP_SYS_ADMIN' Local Privilege Escalation (dbus Method)

    Open source ↗
  • Exploit-DBEDB-47167
    First seen Jan 4, 2019

    Linux Kernel 4.15.x < 4.19.2 - 'map_write() CAP_SYS_ADMIN' Local Privilege Escalation (polkit Method)

    Open source ↗
  • Exploit-DBEDB-45915✓ verified
    First seen Nov 29, 2018

    Linux - Nested User Namespace idmap Limit Local Privilege Escalation (Metasploit)

    Open source ↗
  • Exploit-DBEDB-47164
    First seen Nov 21, 2018

    Linux Kernel 4.15.x < 4.19.2 - 'map_write() CAP_SYS_ADMIN' Local Privilege Escalation (cron Method)

    Open source ↗
  • Exploit-DBEDB-47166
    First seen Nov 21, 2018

    Linux Kernel 4.15.x < 4.19.2 - 'map_write() CAP_SYS_ADMIN' Local Privilege Escalation (ldpreload Method)

    Open source ↗
  • Exploit-DBEDB-45886✓ verified
    First seen Nov 16, 2018

    Linux - Broken uid/gid Mapping for Nested User Namespaces

    Open source ↗
  • Metasploitexploit/linux/local/nested_namespace_idmap_limit_priv_esc✓ verified
    First seen Nov 15, 2018

    Linux Nested User Namespace idmap Limit Local Privilege Escalation

    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2018-18955?
CVE-2018-18955 is a high vulnerability published on November 16, 2018. In the Linux kernel 4.15.x through 4.19.x before 4.19.2, mapwrite() in kernel/usernamespace.c allows privilege escalation because it mishandles nested user namespaces with more than 5 UID or GID ranges. A user who has CAPSYSADMIN in an affected user namespace can bypass access controls on resources…
When was CVE-2018-18955 disclosed?
CVE-2018-18955 was first published in the National Vulnerability Database on November 16, 2018, 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-2018-18955 actively exploited?
CVE-2018-18955 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 93.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2018-18955?
CVE-2018-18955 has a CVSS v3 base score of 7.0 (NVD).
How do I remediate CVE-2018-18955?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2018-18955, 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.

Dependency Blast Radius

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