CVE-2018-12891

MEDIUMNVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

Score 6.5 from GitHub Security Advisory published 2022-05-13. NVD baseline CVSS 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
6.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.5Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

An issue was discovered in Xen through 4.10.x. Certain PV MMU operations may take a long time to process. For that reason Xen explicitly checks for the need to preempt the current vCPU at certain points. A few rarely taken code paths did bypass such checks. By suitably enforcing the conditions through its own page table contents, a malicious guest may cause such bypasses to be used for an unbounded number of iterations. A malicious or buggy PV guest may cause a Denial of Service (DoS) affecting the entire host. Specifically, it may prevent use of a physical CPU for an indeterminate period of time. All Xen versions from 3.4 onwards are vulnerable. Xen versions 3.3 and earlier are vulnerable to an even wider class of attacks, due to them lacking preemption checks altogether in the affected code paths. Only x86 systems are affected. ARM systems are not affected. Only multi-vCPU x86 PV guests can leverage the vulnerability. x86 HVM or PVH guests as well as x86 single-vCPU PV ones cannot leverage the vulnerability.

CVSS v3
6.5
EG Score
6.5(medium)
EPSS
34.9%
KEV
Not listed

Published

July 2, 2018

Last Modified

November 21, 2024

References (16)

Data Freshness Timeline

(refreshed 13× in last 7d / 47× 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. 2026-07-07 13:42 UTCEPSS rescore
  2. 2026-07-07 13:42 UTCEPSS rescore
  3. 2026-07-06 16:24 UTCEPSS rescore
  4. 2026-07-06 16:24 UTCEPSS rescore
  5. 2026-07-06 02:20 UTCEPSS rescore
  6. 2026-07-05 02:27 UTCEPSS rescore
  7. 2026-07-04 06:28 UTCEPSS rescore
  8. 2026-07-04 05:26 UTCOSV refresh
  9. 2026-07-02 16:54 UTCEPSS rescore
  10. 2026-07-01 15:03 UTCEPSS rescore
  11. 2026-07-01 15:03 UTCEPSS rescore
  12. 2026-06-30 23:19 UTCEPSS rescore
  13. 2026-06-30 23:19 UTCEPSS rescore
  14. 2026-06-29 14:03 UTCEPSS rescore
  15. 2026-06-28 14:04 UTCEPSS rescore
  16. 2026-06-28 04:53 UTCEPSS rescore
  17. 2026-06-28 04:53 UTCEPSS rescore
  18. 2026-06-27 03:06 UTCEPSS rescore
  19. 2026-06-25 13:47 UTCEPSS rescore
  20. 2026-06-25 13:47 UTCEPSS rescore
  21. 2026-06-24 14:02 UTCEPSS rescore
  22. 2026-06-24 14:02 UTCEPSS rescore
  23. 2026-06-23 21:30 UTCEPSS rescore
  24. 2026-06-22 14:23 UTCEPSS rescore
  25. 2026-06-21 14:54 UTCEPSS rescore
Show 51 more
  1. 2026-06-21 14:54 UTCEPSS rescore
  2. 2026-06-21 01:57 UTCEPSS rescore
  3. 2026-06-21 01:57 UTCEPSS rescore
  4. 2026-06-19 19:23 UTCEPSS rescore
  5. 2026-06-18 17:50 UTCEPSS rescore
  6. 2026-06-18 17:50 UTCEPSS rescore
  7. 2026-06-17 17:50 UTCEPSS rescore
  8. 2026-06-17 17:50 UTCEPSS rescore
  9. 2026-06-16 17:50 UTCEPSS rescore
  10. 2026-06-16 17:50 UTCEPSS rescore
  11. 2026-06-15 17:45 UTCEPSS rescore
  12. 2026-06-15 17:43 UTCOSV refresh
  13. 2026-06-14 23:14 UTCEPSS rescore
  14. 2026-06-14 23:14 UTCEPSS rescore
  15. 2026-06-13 22:58 UTCEPSS rescore
  16. 2026-06-13 22:58 UTCEPSS rescore
  17. 2026-06-12 23:09 UTCEPSS rescore
  18. 2026-06-11 13:57 UTCEPSS rescore
  19. 2026-06-10 22:16 UTCEPSS rescore
  20. 2026-06-10 13:19 UTCEPSS rescore
  21. 2026-06-08 14:14 UTCEPSS rescore
  22. 2026-06-08 14:14 UTCEPSS rescore
  23. 2026-06-07 15:22 UTCEPSS rescore
  24. 2026-06-07 15:22 UTCEPSS rescore
  25. 2026-06-06 13:45 UTCEPSS rescore
  26. 2026-06-06 13:45 UTCEPSS rescore
  27. 2026-06-05 22:45 UTCEPSS rescore
  28. 2026-06-05 22:44 UTCEPSS rescore
  29. 2026-06-05 06:08 UTCEPSS rescore
  30. 2026-06-05 06:08 UTCEPSS rescore
  31. 2026-06-04 13:10 UTCEPSS rescore
  32. 2026-06-04 13:10 UTCEPSS rescore
  33. 2026-06-02 20:11 UTCEPSS rescore
  34. 2026-06-02 20:11 UTCEPSS rescore
  35. 2026-06-01 13:49 UTCEPSS rescore
  36. 2026-05-31 22:29 UTCEPSS rescore
  37. 2026-05-31 22:28 UTCEPSS rescore
  38. 2026-05-31 00:14 UTCEPSS rescore
  39. 2026-05-31 00:14 UTCEPSS rescore
  40. 2026-05-29 13:41 UTCEPSS rescore
  41. 2026-05-28 13:42 UTCEPSS rescore
  42. 2026-05-28 13:42 UTCEPSS rescore
  43. 2026-05-28 06:09 UTCEG score recompute
  44. 2026-05-28 06:09 UTCGHSA enrichment
  45. 2026-05-27 13:38 UTCEPSS rescore
  46. 2026-05-27 13:38 UTCEPSS rescore
  47. 2026-05-26 13:42 UTCEPSS rescore
  48. 2026-05-26 13:42 UTCEPSS rescore
  49. 2026-05-26 07:17 UTCEPSS rescore
  50. 2026-05-26 07:17 UTCEPSS rescore
  51. 2026-05-23 09:31 UTCOSV refresh

Frequently asked(5)

What is CVE-2018-12891?
CVE-2018-12891 is a medium vulnerability published on July 2, 2018. An issue was discovered in Xen through 4.10.x. Certain PV MMU operations may take a long time to process. For that reason Xen explicitly checks for the need to preempt the current vCPU at certain points. A few rarely taken code paths did bypass such checks. By suitably enforcing the conditions…
When was CVE-2018-12891 disclosed?
CVE-2018-12891 was first published in the National Vulnerability Database on July 2, 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-2018-12891 actively exploited?
CVE-2018-12891 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 34.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2018-12891?
CVE-2018-12891 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2018-12891?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2018-12891, 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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