CVE-2026-48689

CRITICALNVD 9.89.8
EchelonGraph scoreMEDIUM confidence

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

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, GitHub Security Advisory, NVD CVSS v3

Also known asEUVD-2026-31956 (ENISA EUVD) · GHSA-5444-f65m-f3c8 (GitHub Security Advisories)Source: ENISA EUVD

9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.7%CVSS: 9.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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
9.8CRITICALmedium confidence
EG Risk
59
EG Risk 59/100

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)
Severity98% × 45%
Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.7% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (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 at low or medium mission impact and sooner than that at high.
EPSS PROB
0.7%
EPSS %ILE
52nd
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 (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.

EG Severity
9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.7% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). 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 low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days 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 low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (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)3 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (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

May 26, 2026

Last Modified

July 24, 2026

Advisory Details (3)

Auto-updated Oct 31, 2026
Patch available.
Web page

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
Web page

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
Web page

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.

Affected Packages

(2 across 2 ecosystems)
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
fastnetmon1.2.8+git20250911-1, 1.2.8+git20250911-2, 1.2.8-1
  • every version up to 1.2.9-0+deb13u1: fixed in 1.2.9-0+deb13u1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
fastnetmon1.2.8+git20250911-1, 1.2.8+git20250911-2, 1.2.8-1
  • every version up to 1.2.9-1: fixed in 1.2.9-1
—

Weakness Classification(3)

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

Data Freshness Timeline

(refreshed 16× in last 7d / 64× 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 its CVE.org record (CNA or CISA ADP). 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). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 465 rows 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 365 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-12 20:59 UTCEchelonGraph re-scored
  2. 2026-11-12 20:59 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  3. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  4. 2026-11-11 23:14 UTCEchelonGraph re-scored
  5. 2026-11-11 23:14 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  6. 2026-11-11 16:39 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  7. 2026-11-11 01:30 UTCEchelonGraph re-scored
  8. 2026-11-11 01:29 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  9. 2026-11-10 16:44 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  10. 2026-11-10 03:44 UTCEchelonGraph re-scored
  11. 2026-11-10 03:44 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  12. 2026-11-09 16:35 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  13. 2026-11-09 05:59 UTCEchelonGraph re-scored
  14. 2026-11-09 05:59 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  15. 2026-11-08 16:39 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  16. 2026-11-08 08:14 UTCEchelonGraph re-scored
  17. 2026-11-08 08:14 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  18. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  19. 2026-11-07 10:29 UTCEchelonGraph re-scored
  20. 2026-11-07 10:29 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  21. 2026-11-06 16:38 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  22. 2026-11-06 12:44 UTCEchelonGraph re-scored
  23. 2026-11-06 12:44 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  24. 2026-11-06 10:25 UTCOSV refresh
  25. 2026-11-05 16:37 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
Show 75 more
  1. 2026-11-05 14:59 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  2. 2026-11-04 17:14 UTCEchelonGraph re-scored
  3. 2026-11-04 17:14 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  4. 2026-11-04 16:35 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  5. 2026-11-03 19:28 UTCEchelonGraph re-scored
  6. 2026-11-03 19:28 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  7. 2026-11-03 16:48 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  8. 2026-11-02 21:43 UTCEchelonGraph re-scored
  9. 2026-11-02 21:43 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  10. 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  11. 2026-11-01 23:57 UTCEchelonGraph re-scored
  12. 2026-11-01 23:57 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  13. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  14. 2026-11-01 02:13 UTCEchelonGraph re-scored
  15. 2026-11-01 02:13 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  16. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  17. 2026-10-31 04:27 UTCEchelonGraph re-scored
  18. 2026-10-31 04:27 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  19. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  20. 2026-10-30 06:42 UTCEchelonGraph re-scored
  21. 2026-10-30 06:42 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  22. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  23. 2026-10-29 08:57 UTCEchelonGraph re-scored
  24. 2026-10-29 08:57 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  25. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  26. 2026-10-28 11:10 UTCEchelonGraph re-scored
  27. 2026-10-28 11:10 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  28. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  29. 2026-10-27 12:43 UTCEchelonGraph re-scored
  30. 2026-10-27 12:43 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  31. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  32. 2026-10-26 14:58 UTCEchelonGraph re-scored
  33. 2026-10-26 14:58 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  34. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  35. 2026-10-25 16:20 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  36. 2026-10-25 14:23 UTCEchelonGraph re-scored
  37. 2026-10-24 18:34 UTCEchelonGraph re-scored
  38. 2026-10-24 18:34 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  39. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  40. 2026-10-23 20:50 UTCEchelonGraph re-scored
  41. 2026-10-23 20:50 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  42. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  43. 2026-10-22 23:04 UTCEchelonGraph re-scored
  44. 2026-10-22 23:04 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  45. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  46. 2026-10-22 01:19 UTCEchelonGraph re-scored
  47. 2026-10-22 01:19 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  48. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  49. 2026-10-21 03:23 UTCEchelonGraph re-scored
  50. 2026-10-21 03:22 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  51. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  52. 2026-10-20 05:28 UTCEchelonGraph re-scored
  53. 2026-10-20 05:28 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  54. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  55. 2026-10-19 06:54 UTCEchelonGraph re-scored
  56. 2026-10-19 06:54 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  57. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  58. 2026-10-18 09:07 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  59. 2026-10-18 03:34 UTCEchelonGraph re-scored
  60. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  61. 2026-10-17 10:49 UTCEchelonGraph re-scored
  62. 2026-10-17 10:49 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  63. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  64. 2026-10-16 12:23 UTCEchelonGraph re-scored
  65. 2026-10-16 12:23 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  66. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  67. 2026-10-15 14:09 UTCEchelonGraph re-scored
  68. 2026-10-15 14:08 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  69. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  70. 2026-10-14 08:53 UTCEchelonGraph re-scored
  71. 2026-10-14 08:53 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  72. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  73. 2026-10-13 05:09 UTCEchelonGraph re-scored
  74. 2026-10-13 05:09 UTCGHSA enrichmentGHSA-5444-f65m-f3c8 · GitHub severity CRITICAL · GitHub CVSS 9.8
  75. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.9% · 58th percentile

Frequently asked(5)

What is CVE-2026-48689?
CVE-2026-48689 is a critical-severity vulnerability; its CVE record was published on May 26, 2026. 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…
When was the CVE record for CVE-2026-48689 published?
The CVE record for CVE-2026-48689 was published on May 26, 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 July 24, 2026; the record at its source may have been updated since.
Is CVE-2026-48689 actively exploited?
CVE-2026-48689 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.7% probability of exploitation in the next 30 days (52nd percentile of EPSS-scored CVEs).
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?
A fix for CVE-2026-48689 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-48689 are linked in the Vendor Advisories panel on this page.

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