CVE-2026-48689

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-05-26. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 9.8Exploit: NoneExposed: 0

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

FastNetMon Community Edition through 1.2.9 contains an off-by-one heap-based buffer overflow in the dynamic_binary_buffer_t class (src/dynamic_binary_buffer.hpp). Five methods (append_dynamic_buffer, append_data_as_pointer, append_data_as_object_ptr, memcpy_from_ptr, memcpy_from_object_ptr) use an incorrect bounds check of the form 'if (offset + length > maximum_internal_storage_size + 1)' instead of the correct 'if (offset + length > maximum_internal_storage_size)'. This allows writing exactly one byte past the end of the heap-allocated buffer. The class is used pervasively in BGP message encoding/decoding, NetFlow template processing, and Flow Spec NLRI construction. An attacker who can send network traffic (NetFlow, sFlow, IPFIX, or BGP) to a FastNetMon instance can trigger this overflow, potentially achieving arbitrary code execution by corrupting heap metadata. Notably, the append_byte() method uses the correct bounds check, confirming the inconsistency.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
59(Track)
EG Risk 59/100SSVC: 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
Severity98% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
48.4%
KEV
Not listed

Published

May 26, 2026

Last Modified

May 27, 2026

Advisory Details (3)

Auto-updated Jun 20, 2026
No patch confirmed yet.
generic

CVE-2026-48689: A One-Byte Heap Overflow in FastNetMon's Universal Buffer Class | Lorikeet Security

https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48689-dynamic-buffer-off-by-one
generic

fastnetmon/src/dynamic_binary_buffer.hpp at master · pavel-odintsov/fastnetmon · GitHub

https://github.com/pavel-odintsov/fastnetmon/blob/master/src/dynamic_binary_buffer.hpp
generic

GitHub - pavel-odintsov/fastnetmon: Very fast DDoS sensor with sFlow/Netflow/IPFIX/SPAN support · GitHub

https://github.com/pavel-odintsov/fastnetmon

Vendor Advisories for CVE-2026-48689(1)

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

Weakness Classification(3)

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

Data Freshness Timeline

(refreshed 10× 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 197 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-48689?
CVE-2026-48689 is a critical vulnerability published on May 26, 2026. FastNetMon Community Edition through 1.2.9 contains an off-by-one heap-based buffer overflow in the dynamicbinarybuffert class (src/dynamicbinarybuffer.hpp). Five methods (appenddynamicbuffer, appenddataaspointer, appenddataasobjectptr, memcpyfromptr, memcpyfromobjectptr) use an incorrect bounds…
When was CVE-2026-48689 disclosed?
CVE-2026-48689 was first published in the National Vulnerability Database on May 26, 2026, with the most recent update on May 27, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-48689 actively exploited?
CVE-2026-48689 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 48.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-48689?
CVE-2026-48689 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-48689?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-48689, 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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