CVE-2026-48686

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
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.8Exploit: None knownExposed: 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 a stack-based buffer overflow in the BGP NLRI (Network Layer Reachability Information) decoder. The function decode_bgp_subnet_encoding_ipv4_raw() in src/bgp_protocol.cpp reads prefix_bit_length directly from the BGP packet (line 99) without validating it is <= 32 for IPv4 prefixes. This value is passed to how_much_bytes_we_need_for_storing_certain_subnet_mask() which computes ceil(prefix_bit_length / 8), returning up to 32 bytes for a prefix_bit_length of 255. The result is used as the length argument to memcpy() (line 106), which copies into a 4-byte uint32_t stack variable (prefix_ipv4). This causes a stack buffer overflow of up to 28 bytes, which can be exploited for arbitrary code execution. Additionally, the unvalidated prefix_bit_length is passed to convert_cidr_to_binary_netmask_local_function_copy() (line 111), where a shift of (32 - cidr) with cidr > 32 causes undefined behavior.

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 PROB
1%
EPSS %ILE
45%
KEV
Not listed

Published

May 26, 2026

Last Modified

July 24, 2026

Advisory Details (3)

Auto-updated Sep 11, 2026
No patch confirmed yet.
generic

CVE-2026-48686: 28-Byte Stack Overflow in FastNetMon BGP NLRI Decoder | Lorikeet Security

https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48686-bgp-nlri-stack-overflow
generic

fastnetmon/src/bgp_protocol.cpp at master · pavel-odintsov/fastnetmon · GitHub

https://github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.cpp
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-2026-48686(1)

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

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
fastnetmon1.2.4-2 ... 1.2.9-1 (14 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
fastnetmon1.2.8+git20250911-1, 1.2.8+git20250911-2, 1.2.8-11.2.9-0+deb13u1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
fastnetmon1.2.8+git20250911-1, 1.2.8+git20250911-2, 1.2.8-11.2.9-1—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 5× in last 7d / 37× 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 333 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-48686?
CVE-2026-48686 is a critical vulnerability published on May 26, 2026. FastNetMon Community Edition through 1.2.9 contains a stack-based buffer overflow in the BGP NLRI (Network Layer Reachability Information) decoder. The function decodebgpsubnetencodingipv4raw() in src/bgpprotocol.cpp reads prefixbitlength directly from the BGP packet (line 99) without validating it…
When was CVE-2026-48686 disclosed?
CVE-2026-48686 was first published in the National Vulnerability Database on May 26, 2026, with the most recent update on July 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-48686 actively exploited?
CVE-2026-48686 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 54.7% of all scored CVEs.
What is the CVSS score of CVE-2026-48686?
CVE-2026-48686 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-48686?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-48686, 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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