CVE-2026-43491

MEDIUMNVD 5.55.5
EchelonGraph scoreMEDIUM confidence

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

Score 5.5 from GitHub Security Advisory (severity: MODERATE) published 2026-05-19. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 4 sources updated this week

Also known asEUVD-2026-30880 (ENISA EUVD) · GHSA-vfqf-4c37-r857 (GitHub Security Advisories)Source: ENISA EUVD

5.5EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 5.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

In the Linux kernel, the following vulnerability has been resolved:

net: qrtr: ns: Limit the maximum server registration per node

Current code does no bound checking on the number of servers added per node. A malicious client can flood NEW_SERVER messages and exhaust memory.

Fix this issue by limiting the maximum number of server registrations to 256 per node. If the NEW_SERVER message is received for an old port, then don't restrict it as it will get replaced. While at it, also rate limit the error messages in the failure path of qrtr_ns_worker().

Note that the limit of 256 is chosen based on the current platform requirements. If requirement changes in the future, this limit can be increased.

CVSS v3
5.5
EG Score
5.5MEDIUMmedium confidence
EG Risk
25
EG Risk 25/100

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)
Severity55% × 45%
Impact severity (EG Severity): CVSS 5.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.1% × 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 every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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
0.1%
EPSS %ILE
4th
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 (5.5): severity, escalated by confirmed exploitation. This CVE's 5.5 is its impact severity (EG Severity), not escalated.

EG Severity
5.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.1% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-05). 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 every mission impact level.CISA BOD 26-04: 60 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 every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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)60 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 Vulnrichment) · Technical impact partial (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

May 19, 2026

Last Modified

November 6, 2026

Advisory Details (5)

Auto-updated Jun 26, 2026
Patch available.
Web page

net: qrtr: ns: Limit the maximum server registration per node - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/e6f6cd501fb54060940a6eb3f4103eeb5e426ae7
Web page

net: qrtr: ns: Limit the maximum server registration per node - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/d5ee2ff98322337951c56398e79d51815acbf955
Web page

net: qrtr: ns: Limit the maximum server registration per node - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/868202aa2adae427060a42d5bd663b4d782ec02c
Web page

net: qrtr: ns: Limit the maximum server registration per node - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/3efaad55cad1ded429e3a873bfece389058a526b
Web page

net: qrtr: ns: Limit the maximum server registration per node - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/35fb4a0c077c5d1049c2628b769e0a1b1e65df0d

Vendor Advisories for CVE-2026-43491(2)

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

Patch Availability(28)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulinux-tools-nvidia-lowlatency-64k-6.8 (6.8.0-1059.62.1) @ noble2026-10-23ubuntu
ubuntulinux-tools-azure-fde-lts-22.04 (5.15.0.1122.131) @ jammy2026-10-23ubuntu
ubuntulinux-virtual-hwe-26.04-edge (7.0.0-27.27) @ resolute2026-10-23ubuntu
ubuntulinux-tools-gcp-edge (5.15.0.1118.128~20.04.1) @ focal2026-10-23ubuntu
ubuntulinux-virtual-hwe-22.04-edge (6.8.0-136.136~22.04.1) @ jammy2026-10-23ubuntu
ubuntulinux-tools-oracle-edge (5.15.0.1114.120~20.04.1) @ focal2026-10-23ubuntu
ubuntulinux-tools-realtime-hwe-22.04 (6.8.1-1056.57~22.04.2) @ jammy2026-10-23ubuntu
ubuntulinux-tools-oracle-lts-24.04 (6.8.0-1058.61) @ noble2026-10-23ubuntu
ubuntulinux-tools-azure-fde-7.0 (7.0.0-1009.9) @ resolute2026-10-23ubuntu
ubuntulinux-tools-aws-lts-24.04 (6.8.0-1061.64+1) @ noble2026-10-23ubuntu
ubuntulinux-tools-azure-edge (6.8.0-1063.71~22.04.1) @ jammy2026-10-23ubuntu
ubuntulinux-tools-azure-fde-lts-24.04 (6.8.0-1062.69) @ noble2026-10-23ubuntu
ubuntulinux-tools-azure-fde-6.8 (6.8.0-1062.69~22.04.1) @ jammy2026-10-23ubuntu
ubuntulinux-tools-gcp-lts-22.04 (5.15.0.1118.115) @ jammy2026-10-23ubuntu
ubuntulinux-xilinx-zynqmp-tools-5.15.0-1080 (5.15.0-1080.84) @ jammy2026-10-23ubuntu
ubuntulinux-tools-nvidia-lowlatency-5.15 (5.15.0.1112.112) @ jammy2026-10-23ubuntu
ubuntulinux-tools-oem-7.0 (7.0.0-1008.8) @ resolute2026-10-23ubuntu
ubuntulinux-tools-raspi-realtime-7.0 (7.0.0-1014.14) @ resolute2026-10-23ubuntu
ubuntulinux-tools-nvidia-hwe-24.04-edge (7.0.0-1013.13) @ resolute2026-10-23ubuntu
ubuntulinux-virtual-hwe-24.04-edge (7.0.0-28.28~24.04.1) @ noble2026-10-23ubuntu
ubuntulinux-tools-oracle-edge (6.8.0-1058.61~22.04.1) @ jammy2026-10-23ubuntu
ubuntulinux-tools-azure-fips-6.8 (6.8.0-1063.71+fips2) @ noble2026-10-23ubuntu
ubuntulinux-tools-raspi-realtime-6.8 (6.8.0-2050.52) @ noble2026-10-23ubuntu
ubuntulinux-tools-aws-fips-6.8 (6.8.0-1061.64+fips1) @ noble2026-10-23ubuntu
ubuntulinux-xilinx-zynqmp (6.8.0.1033.34) @ noble2026-10-23ubuntu
ubuntulinux-tools-gcp-fips-6.8 (6.8.0-1064.72+fips1) @ noble2026-10-23ubuntu
linuxKernel @ 5.10.265 (fixes >=5.7.0)—osv
linuxKernel @ 6.6.140 (fixes >=5.7.0)—osv

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

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
linux5.10.103-1 ... 7.2~rc5-1~exp1 (496 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.1.106-1 ... 6.1.99-1 (56 versions)
  • every version up to 6.1.187-1: fixed in 6.1.187-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.38-1 ... 6.12.86-1~bpo12+1 (19 versions)
  • every version up to 6.12.86-1: fixed in 6.12.86-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.0.4-1~bpo13+1 (135 versions)
  • every version up to 7.0.4-1: fixed in 7.0.4-1
—

Additional Vendor Advisories

(24)

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 12× in last 7d / 45× 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 100 of 253 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. None are among the latest 100 rows. The 153 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-06 16:38 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  2. 2026-11-06 16:31 UTCVendor advisory
  3. 2026-11-06 16:31 UTCGHSA enrichmentGHSA-vfqf-4c37-r857 · GitHub severity MODERATE · GitHub CVSS 5.5
  4. 2026-11-06 15:49 UTCEG score recompute
  5. 2026-11-06 15:49 UTCVendor advisory
  6. 2026-11-06 15:49 UTCGHSA enrichmentGHSA-vfqf-4c37-r857 · GitHub severity MODERATE · GitHub CVSS 5.5
  7. 2026-11-05 16:37 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  8. 2026-11-04 16:35 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  9. 2026-11-03 16:48 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  10. 2026-11-02 16:44 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  11. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  12. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  13. 2026-10-30 16:55 UTCOSV refresh
  14. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  15. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  16. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  17. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  18. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  19. 2026-10-25 14:28 UTCEG score recompute
  20. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  21. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  22. 2026-10-23 01:40 UTCEG score recompute
  23. 2026-10-23 01:40 UTCVendor advisory
  24. 2026-10-23 01:39 UTCGHSA enrichmentGHSA-vfqf-4c37-r857 · GitHub CVSS 5.5
  25. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
Show 75 more
  1. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  2. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  3. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  4. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  5. 2026-10-18 03:40 UTCEG score recompute
  6. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  7. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  8. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  9. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  10. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  11. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  12. 2026-10-12 16:06 UTCEG score recompute
  13. 2026-10-11 19:48 UTCEG score recompute
  14. 2026-10-11 17:02 UTCEG score recompute
  15. 2026-10-11 14:28 UTCEG score recompute
  16. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  17. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  18. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  19. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  20. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  21. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  22. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  23. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  24. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  25. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  26. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  27. 2026-09-30 03:39 UTCOSV refresh
  28. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  29. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  30. 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  31. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  32. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  33. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  34. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  35. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  36. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  37. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  38. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  39. 2026-09-11 05:53 UTCOSV refresh
  40. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  41. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  42. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  43. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  44. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  45. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  46. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  47. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  48. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  49. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  50. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  51. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  52. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  53. 2026-08-23 17:09 UTCEG score recompute
  54. 2026-08-23 17:09 UTCVendor advisory
  55. 2026-08-23 17:08 UTCGHSA enrichmentGHSA-vfqf-4c37-r857 · GitHub CVSS 5.5
  56. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  57. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  58. 2026-08-21 23:39 UTCEG score recompute
  59. 2026-08-21 23:39 UTCVendor advisory
  60. 2026-08-21 23:39 UTCGHSA enrichmentGHSA-vfqf-4c37-r857 · GitHub CVSS 5.5
  61. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  62. 2026-08-20 19:06 UTCVendor advisory
  63. 2026-08-20 19:05 UTCGHSA enrichmentGHSA-vfqf-4c37-r857 · GitHub CVSS 5.5
  64. 2026-08-19 17:51 UTCEG score recompute
  65. 2026-08-19 17:51 UTCVendor advisory
  66. 2026-08-19 17:51 UTCGHSA enrichmentGHSA-vfqf-4c37-r857 · GitHub CVSS 5.5
  67. 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  68. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  69. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  70. 2026-08-17 10:02 UTCEG score recompute
  71. 2026-08-17 10:02 UTCVendor advisory
  72. 2026-08-17 10:02 UTCGHSA enrichmentGHSA-vfqf-4c37-r857 · GitHub CVSS 5.5
  73. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  74. 2026-08-16 03:37 UTCEG score recompute
  75. 2026-08-16 03:37 UTCVendor advisory

Frequently asked(5)

What is CVE-2026-43491?
CVE-2026-43491 is a medium-severity vulnerability; its CVE record was published on May 19, 2026. In the Linux kernel, the following vulnerability has been resolved: net: qrtr: ns: Limit the maximum server registration per node Current code does no bound checking on the number of servers added per node. A malicious client can flood NEW_SERVER messages and exhaust memory. Fix this issue by…
When was the CVE record for CVE-2026-43491 published?
The CVE record for CVE-2026-43491 was published on May 19, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of November 6, 2026; the record at its source may have been updated since.
Is CVE-2026-43491 actively exploited?
CVE-2026-43491 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.1% probability of exploitation in the next 30 days (4th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-43491?
CVE-2026-43491 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2026-43491?
A fix for CVE-2026-43491 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-43491 are linked in the Vendor Advisories panel on this page.

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