CVE-2026-23300

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2026-03-25. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
5.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.5Exploit: NoneExposed: 0

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

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

net: ipv6: fix panic when IPv4 route references loopback IPv6 nexthop

When a standalone IPv6 nexthop object is created with a loopback device (e.g., "ip -6 nexthop add id 100 dev lo"), fib6_nh_init() misclassifies it as a reject route. This is because nexthop objects have no destination prefix (fc_dst=::), causing fib6_is_reject() to match any loopback nexthop. The reject path skips fib_nh_common_init(), leaving nhc_pcpu_rth_output unallocated. If an IPv4 route later references this nexthop, __mkroute_output() dereferences NULL nhc_pcpu_rth_output and panics.

Simplify the check in fib6_nh_init() to only match explicit reject routes (RTF_REJECT) instead of using fib6_is_reject(). The loopback promotion heuristic in fib6_is_reject() is handled separately by ip6_route_info_create_nh(). After this change, the three cases behave as follows:

  • Explicit reject route ("ip -6 route add unreachable 2001:db8::/64"):
RTF_REJECT is set, enters reject path, skips fib_nh_common_init(). No behavior change.
  • Implicit loopback reject route ("ip -6 route add 2001:db8::/32 dev lo"):
RTF_REJECT is not set, takes normal path, fib_nh_common_init() is called. ip6_route_info_create_nh() still promotes it to reject afterward. nhc_pcpu_rth_output is allocated but unused, which is harmless.
  • Standalone nexthop object ("ip -6 nexthop add id 100 dev lo"):
RTF_REJECT is not set, takes normal path, fib_nh_common_init() is called. nhc_pcpu_rth_output is properly allocated, fixing the crash when IPv4 routes reference this nexthop.

CVSS v3
5.5
EG Score
5.5(medium)
EPSS
2.9%
KEV
Not listed

Published

March 25, 2026

Last Modified

July 14, 2026

References (10)

Vendor Advisories for CVE-2026-23300(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 / EcosystemFixed in / PatchReleasedSource
linuxKernel @ 6.1.167—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.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 52× 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.

Showing the most recent 100 of 124 total refreshes for this CVE.

  1. 2026-07-15 16:57 UTCEPSS rescore
  2. 2026-07-15 16:57 UTCEPSS rescore
  3. 2026-07-15 02:00 UTCEPSS rescore
  4. 2026-07-15 02:00 UTCEPSS rescore
  5. 2026-07-14 13:19 UTCNVD updateCVSS v3 → 5.5 · severity → MEDIUM
  6. 2026-07-14 13:11 UTCMITRE cvelistV5
  7. 2026-07-13 22:30 UTCEPSS rescore
  8. 2026-07-13 06:13 UTCEPSS rescore
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  10. 2026-07-12 05:46 UTCEPSS rescore
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  1. 2026-06-30 23:22 UTCEPSS rescore
  2. 2026-06-30 23:22 UTCEPSS rescore
  3. 2026-06-29 14:06 UTCEPSS rescore
  4. 2026-06-29 05:02 UTCOSV refresh
  5. 2026-06-28 14:07 UTCEPSS rescore
  6. 2026-06-28 14:07 UTCEPSS rescore
  7. 2026-06-28 04:56 UTCEPSS rescore
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  9. 2026-06-27 03:08 UTCEPSS rescore
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  20. 2026-06-21 01:59 UTCEPSS rescore
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  22. 2026-06-19 19:25 UTCEPSS rescore
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  24. 2026-06-18 17:52 UTCEPSS rescore
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  26. 2026-06-17 17:53 UTCEPSS rescore
  27. 2026-06-16 17:52 UTCEPSS rescore
  28. 2026-06-15 17:48 UTCEPSS rescore
  29. 2026-06-14 23:18 UTCEPSS rescore
  30. 2026-06-13 23:00 UTCEPSS rescore
  31. 2026-06-13 23:00 UTCEPSS rescore
  32. 2026-06-12 23:12 UTCEPSS rescore
  33. 2026-06-11 23:32 UTCEG score recompute
  34. 2026-06-11 23:32 UTCVendor advisory
  35. 2026-06-11 23:32 UTCGHSA enrichment
  36. 2026-06-11 14:00 UTCEPSS rescore
  37. 2026-06-10 22:18 UTCEPSS rescore
  38. 2026-06-10 15:01 UTCEG score recompute
  39. 2026-06-10 15:01 UTCVendor advisory
  40. 2026-06-10 15:01 UTCGHSA enrichment
  41. 2026-06-10 13:22 UTCEPSS rescore
  42. 2026-06-09 15:58 UTCEG score recompute
  43. 2026-06-09 15:58 UTCVendor advisory
  44. 2026-06-09 15:58 UTCGHSA enrichment
  45. 2026-06-08 14:34 UTCEG score recompute
  46. 2026-06-08 14:34 UTCVendor advisory
  47. 2026-06-08 14:34 UTCGHSA enrichment
  48. 2026-06-08 14:17 UTCEPSS rescore
  49. 2026-06-08 14:17 UTCEPSS rescore
  50. 2026-06-07 15:25 UTCEPSS rescore
  51. 2026-06-07 15:24 UTCEPSS rescore
  52. 2026-06-07 12:35 UTCEG score recompute▲ 5.50
  53. 2026-06-07 12:35 UTCVendor advisory
  54. 2026-06-07 12:35 UTCGHSA enrichment
  55. 2026-06-06 13:47 UTCEPSS rescore
  56. 2026-06-06 13:47 UTCEPSS rescore
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  66. 2026-06-01 13:51 UTCEPSS rescore
  67. 2026-06-01 13:51 UTCEPSS rescore
  68. 2026-06-01 13:51 UTCEPSS rescore
  69. 2026-06-01 07:13 UTCOSV refresh
  70. 2026-05-31 22:30 UTCEPSS rescore
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  72. 2026-05-31 00:16 UTCEPSS rescore
  73. 2026-05-31 00:16 UTCEPSS rescore
  74. 2026-05-31 00:16 UTCEPSS rescore
  75. 2026-05-29 13:44 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2026-23300?
CVE-2026-23300 is a medium vulnerability published on March 25, 2026. In the Linux kernel, the following vulnerability has been resolved: net: ipv6: fix panic when IPv4 route references loopback IPv6 nexthop When a standalone IPv6 nexthop object is created with a loopback device (e.g., "ip -6 nexthop add id 100 dev lo"), fib6nhinit() misclassifies it as a reject…
When was CVE-2026-23300 disclosed?
CVE-2026-23300 was first published in the National Vulnerability Database on March 25, 2026, with the most recent update on July 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-23300 actively exploited?
CVE-2026-23300 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-23300?
CVE-2026-23300 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2026-23300?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-23300, 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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