CVE-2026-3842

HIGHPre-NVD 7.87.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-07-16. A secondary CVSS source baseline 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
7.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 7.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

A flaw was found in QEMU. This vulnerability allows a local attacker within a guest virtual machine to write data beyond its allocated memory. This occurs when cpu_physical_memory_map() returns a shorter length than expected, leading to an out-of-bounds write. Successful exploitation could result in unauthorized access to guest memory or corruption of heap-allocated objects, potentially causing information disclosure, data integrity issues, or a denial of service.

CVSS v3
7.8
EG Score
7.8HIGHmedium confidence
EG Risk
35
EG Risk 35/100

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 (value × EchelonGraph’s weight)
Severity78% × 45%
The EG Score, 7.8 of 10.
Exploitation0.2% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (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
0.2%
EPSS %ILE
5th
KEV
Not listed

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 (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (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.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). 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

July 16, 2026

Last Modified

September 1, 2026

Advisory Details (2)

Auto-updated Jul 16, 2026
Patch available. Sources: redhat.
Red Hat

2458150 – (CVE-2026-3842) CVE-2026-3842 qemu-kvm: hyperv/syndbg: missing mapped-length guard after cpu_physical_memory_map causes host OOB write

https://bugzilla.redhat.com/show_bug.cgi?id=2458150
Red HatMentions a patch (unverified)

cve-details

https://access.redhat.com/security/cve/CVE-2026-3842

Vendor Advisories for CVE-2026-3842(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntuqemu-utils (1:10.1.0+ds-5ubuntu2.6) @ questing2026-10-01ubuntu

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

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
qemu1:10.0.0+ds-1 ... 1:9.2.2+ds-1~bpo12+1 (200 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
qemu1:10.0.2+ds-2 ... 1:10.0.8+ds-0+deb13u1 (12 versions)
  • every version up to 1:10.0.10+ds-0+deb13u1: fixed in 1:10.0.10+ds-0+deb13u1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
qemu1:10.0.2+ds-2 ... 1:10.2.1+ds-1 (31 versions)
  • every version up to 1:10.2.2+ds-1: fixed in 1:10.2.2+ds-1
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 11× in last 7d / 41× 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 304 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 205 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  3. 2026-10-12 16:10 UTCEG score recompute
  4. 2026-10-11 19:53 UTCEG score recompute
  5. 2026-10-11 17:06 UTCEG score recompute
  6. 2026-10-11 14:33 UTCEG score recompute
  7. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  9. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  10. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  11. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  12. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  13. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  14. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  15. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  16. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  17. 2026-10-01 12:34 UTCEG score recompute
  18. 2026-10-01 12:34 UTCVendor advisory
  19. 2026-10-01 12:34 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  20. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  21. 2026-09-28 08:39 UTCEG score recompute
  22. 2026-09-28 08:39 UTCVendor advisory
  23. 2026-09-28 08:39 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  24. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  25. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.2% · 5th percentile
Show 74 more
  1. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  2. 2026-09-24 08:43 UTCEG score recompute
  3. 2026-09-24 08:43 UTCVendor advisory
  4. 2026-09-24 08:43 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  5. 2026-09-23 03:11 UTCEG score recompute
  6. 2026-09-23 03:11 UTCVendor advisory
  7. 2026-09-23 03:11 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  8. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  9. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  10. 2026-09-18 04:41 UTCEG score recompute
  11. 2026-09-18 04:41 UTCVendor advisory
  12. 2026-09-18 04:41 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  13. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  14. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  15. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  16. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  17. 2026-09-14 10:23 UTCVendor advisory
  18. 2026-09-14 10:23 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  19. 2026-09-13 23:10 UTCEG score recompute
  20. 2026-09-13 23:10 UTCVendor advisory
  21. 2026-09-13 23:10 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  22. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  23. 2026-09-13 07:10 UTCEG score recompute
  24. 2026-09-13 07:10 UTCVendor advisory
  25. 2026-09-13 07:10 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  26. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  27. 2026-09-12 12:54 UTCVendor advisory
  28. 2026-09-12 12:54 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  29. 2026-09-11 21:43 UTCEG score recompute
  30. 2026-09-11 21:43 UTCVendor advisory
  31. 2026-09-11 21:43 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  32. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  33. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  34. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  35. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  36. 2026-09-08 00:39 UTCEG score recompute
  37. 2026-09-08 00:39 UTCVendor advisory
  38. 2026-09-08 00:39 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  39. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  40. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  41. 2026-09-06 13:27 UTCVendor advisory
  42. 2026-09-06 13:27 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  43. 2026-09-05 20:44 UTCEG score recompute
  44. 2026-09-05 20:44 UTCVendor advisory
  45. 2026-09-05 20:44 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  46. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  47. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  48. 2026-09-01 13:42 UTCEG score recompute
  49. 2026-09-01 13:42 UTCVendor advisory
  50. 2026-09-01 13:42 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  51. 2026-09-01 12:18 UTCEG score recompute
  52. 2026-09-01 12:18 UTCVendor advisory
  53. 2026-09-01 12:18 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  54. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  55. 2026-08-31 03:45 UTCEG score recompute
  56. 2026-08-31 03:45 UTCVendor advisory
  57. 2026-08-31 03:45 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  58. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  59. 2026-08-30 16:00 UTCVendor advisory
  60. 2026-08-30 16:00 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  61. 2026-08-30 03:41 UTCEG score recompute
  62. 2026-08-30 03:41 UTCVendor advisory
  63. 2026-08-30 03:41 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  64. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  65. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  66. 2026-08-27 23:53 UTCEG score recompute
  67. 2026-08-27 23:53 UTCVendor advisory
  68. 2026-08-27 23:53 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  69. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  70. 2026-08-27 12:35 UTCVendor advisory
  71. 2026-08-27 12:35 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8
  72. 2026-08-26 23:05 UTCEG score recompute
  73. 2026-08-26 23:05 UTCVendor advisory
  74. 2026-08-26 23:05 UTCGHSA enrichmentGHSA-6mwr-p34x-55cv · GitHub severity HIGH · GitHub CVSS 7.8

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Frequently asked(5)

What is CVE-2026-3842?
CVE-2026-3842 is a high-severity vulnerability; its CVE record was published on July 16, 2026. A flaw was found in QEMU. This vulnerability allows a local attacker within a guest virtual machine to write data beyond its allocated memory. This occurs when cpuphysicalmemory_map() returns a shorter length than expected, leading to an out-of-bounds write. Successful exploitation could result in…
When was CVE-2026-3842 made public?
CVE-2026-3842 was made public on March 9, 2026: that is the date its CVE record's CNA, Fedora Project, gives for when the vulnerability was made public. The CVE record itself was published on July 16, 2026. EchelonGraph's copy of the record carries a last-modified date of September 1, 2026; the record at its source may have been updated since.
Is CVE-2026-3842 actively exploited?
CVE-2026-3842 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (5th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-3842?
CVE-2026-3842 has a CVSS base score of 7.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-3842?
A fix for CVE-2026-3842 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-3842 are linked in the Vendor Advisories panel on this page.

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