CVE-2025-24356

HIGHNVD 7.57.5
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.7% (52nd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3

Also known asEUVD-2025-3677 (ENISA EUVD)Source: ENISA EUVD

7.5EG
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: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

fastd is a VPN daemon which tunnels IP packets and Ethernet frames over UDP. When receiving a data packet from an unknown IP address/port combination, fastd will assume that one of its connected peers has moved to a new address and initiate a reconnect by sending a handshake packet. This "fast reconnect" avoids having to wait for a session timeout (up to ~90s) until a new connection is established. Even a 1-byte UDP packet just containing the fastd packet type header can trigger a much larger handshake packet (~150 bytes of UDP payload). Including IPv4 and UDP headers, the resulting amplification factor is roughly 12-13. By sending data packets with a spoofed source address to fastd instances reachable on the internet, this amplification of UDP traffic might be used to facilitate a Distributed Denial of Service attack. This vulnerability is fixed in v23.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100

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)
Severity75% × 45%
Impact severity (EG Severity): CVSS 7.5 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 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 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 (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.

EG Severity
7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.7% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-27). 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: 14 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 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)14 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 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

January 27, 2025

Last Modified

August 27, 2025

Advisory Details (8)

Auto-updated Oct 18, 2026
Patch available. Sources: github, github_commit.
GitHub advisoryMentions a patch (unverified)

UDP traffic amplification via fastd's fast reconnect feature · Advisory · neocturne/fastd · GitHub

https://github.com/neocturne/fastd/security/advisories/GHSA-pggg-vpfv-4rcv
GitHub commit Patch Available

commit d03a0a17347e (neocturne/fastd)

Patch available: neocturne/fastd v23 (contains commit d03a0a17347e)

https://github.com/neocturne/fastd/commit/d03a0a17347efb5293e42fde7d982781e90f14ef
GitHub commit Patch Available

commit ce1b79b12dbf (neocturne/fastd)

Patch available: neocturne/fastd v23 (contains commit ce1b79b12dbf)

https://github.com/neocturne/fastd/commit/ce1b79b12dbfa796743b5f3a50789ade965b7023
GitHub commit Patch Available

commit c1a07b3f2b90 (neocturne/fastd)

Patch available: neocturne/fastd v23 (contains commit c1a07b3f2b90)

https://github.com/neocturne/fastd/commit/c1a07b3f2b9066c3713c68547da700b85d60f4f7
GitHub commit Patch Available

commit 9df7e5163784 (neocturne/fastd)

Patch available: neocturne/fastd v23 (contains commit 9df7e5163784)

https://github.com/neocturne/fastd/commit/9df7e516378441d2d17b89f9db5c27c8312d8f12
GitHub commit Patch Available

commit 5f63fcfc18ae (neocturne/fastd)

Patch available: neocturne/fastd v23 (contains commit 5f63fcfc18ae)

https://github.com/neocturne/fastd/commit/5f63fcfc18ae9cad023fa463b152d5e14192b5a8
GitHub commit Patch Available

commit 3940150e801d (neocturne/fastd)

Patch available: neocturne/fastd v23 (contains commit 3940150e801d)

https://github.com/neocturne/fastd/commit/3940150e801d0c91460491bec32cbcc5bbc89d5f
GitHub commit Patch Available

commit 1f233bee76b7 (neocturne/fastd)

Patch available: neocturne/fastd v23 (contains commit 1f233bee76b7)

https://github.com/neocturne/fastd/commit/1f233bee76b722c0b3f9024f2c39c72e9f7e5843

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
fastd21-1 ... 23-2 (10 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
fastd22-4, 23-1, 23-2
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
fastd—
  • every version up to 23-1: fixed in 23-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
fastd—
  • every version up to 23-1: fixed in 23-1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 38× 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 96 of 193 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. 4 repeat rows among the latest 100 are merged into the row they repeat. The 97 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  2. 2026-10-31 16:30 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  3. 2026-10-30 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  4. 2026-10-29 16:31 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  5. 2026-10-28 16:30 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  6. 2026-10-27 17:22 UTCEG score recompute
  7. 2026-10-27 16:30 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  8. 2026-10-26 16:29 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  9. 2026-10-25 16:40 UTCEG score recompute
  10. 2026-10-25 16:31 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  11. 2026-10-24 16:30 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  12. 2026-10-23 16:30 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  13. 2026-10-22 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  14. 2026-10-21 16:30 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  15. 2026-10-20 16:31 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  16. 2026-10-19 16:30 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  17. 2026-10-18 19:47 UTCEG score recompute
  18. 2026-10-18 16:30 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  19. 2026-10-18 05:43 UTCEG score recompute
  20. 2026-10-17 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  21. 2026-10-16 16:38 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  22. 2026-10-15 16:30 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  23. 2026-10-14 16:31 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  24. 2026-10-13 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  25. 2026-10-12 17:17 UTCEG score recompute
Show 71 more
  1. 2026-10-12 16:32 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  2. 2026-10-11 20:48 UTCEG score recompute
  3. 2026-10-11 18:59 UTCEG score recompute
  4. 2026-10-11 15:37 UTCEG score recompute
  5. 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  6. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  7. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  8. 2026-10-08 17:09 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  9. 2026-10-07 23:46 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  10. 2026-10-06 15:16 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  11. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  12. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  13. 2026-10-03 14:24 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  14. 2026-10-03 00:40 UTCOSV refresh
  15. 2026-10-02 16:26 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  16. 2026-10-01 19:48 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  17. 2026-09-30 15:02 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  18. 2026-09-28 13:50 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  19. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  20. 2026-09-26 00:24 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  21. 2026-09-24 14:02 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  22. 2026-09-23 13:46 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  23. 2026-09-22 14:47 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  24. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  25. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  26. 2026-09-16 14:06 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  27. 2026-09-16 05:13 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  28. 2026-09-15 03:09 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  29. 2026-09-13 22:09 UTCOSV refresh
  30. 2026-09-13 16:46 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  31. 2026-09-12 15:00 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  32. 2026-09-11 14:51 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  33. 2026-09-11 09:35 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  34. 2026-09-10 09:33 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  35. 2026-09-08 21:59 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  36. 2026-09-07 16:00 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  37. 2026-09-06 13:46 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  38. 2026-09-05 15:28 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  39. 2026-09-04 05:05 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  40. 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  41. 2026-09-01 13:52 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  42. 2026-09-01 04:38 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  43. 2026-08-30 19:16 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  44. 2026-08-30 01:21 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  45. 2026-08-28 21:40 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  46. 2026-08-27 14:24 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  47. 2026-08-25 23:39 UTCOSV refresh
  48. 2026-08-25 13:47 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  49. 2026-08-23 00:18 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  50. 2026-08-21 23:48 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  51. 2026-08-20 22:54 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  52. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  53. 2026-08-18 13:47 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  54. 2026-08-17 13:46 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  55. 2026-08-16 14:55 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  56. 2026-08-16 02:13 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  57. 2026-08-15 01:29 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  58. 2026-08-13 21:59 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  59. 2026-08-12 13:50 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  60. 2026-08-10 23:59 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  61. 2026-08-09 16:10 UTCOSV refresh
  62. 2026-08-09 13:45 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  63. 2026-08-07 16:26 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  64. 2026-08-06 13:46 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  65. 2026-08-05 19:16 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  66. 2026-08-04 15:09 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  67. 2026-08-04 10:37 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  68. 2026-08-02 02:25 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  69. 2026-08-01 04:15 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  70. 2026-07-30 16:27 UTCEPSS rescoreEPSS 0.7% · 48th percentile
  71. 2026-07-30 01:29 UTCEPSS rescoreEPSS 0.7% · 47th percentile

Frequently asked(5)

What is CVE-2025-24356?
CVE-2025-24356 is a high-severity vulnerability; its CVE record was published on January 27, 2025. fastd is a VPN daemon which tunnels IP packets and Ethernet frames over UDP. When receiving a data packet from an unknown IP address/port combination, fastd will assume that one of its connected peers has moved to a new address and initiate a reconnect by sending a handshake packet. This "fast…
When was the CVE record for CVE-2025-24356 published?
The CVE record for CVE-2025-24356 was published on January 27, 2025. 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 August 27, 2025; the record at its source may have been updated since.
Is CVE-2025-24356 actively exploited?
CVE-2025-24356 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-2025-24356?
CVE-2025-24356 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2025-24356?
A fix for CVE-2025-24356 is available: update to the fixed version the vendor names in its advisory.

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