CVE-2026-54571

HIGHPre-NVD 8.78.7
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 8.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (44th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source

Also known asEUVD-2026-82385 (ENISA EUVD)Source: ENISA EUVD

8.7EG
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: 0.5%CVSS: 8.7Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

ESPAsyncWebServer is an asynchronous HTTP and WebSocket server library for ESP32, ESP8266, RP2040 and RP2350. Prior to 3.11.1, the multipart/form-data parser in src/WebRequest.cpp stores _boundaryPosition as an 8-bit value while _parseMultipartPostByte processes the boundary. A remote request containing an exactly 256-byte multipart boundary wraps _boundaryPosition from 255 to zero, prevents the boundary parsing loop from terminating, consumes excessive CPU, and triggers a FreeRTOS watchdog reset on affected ESP32 or ESP8266 devices. This issue is fixed in version 3.11.1.

CVSS v3
8.7
EG Score
8.7HIGHmedium confidence
EG Risk
54
EG Risk 54/100

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)
Severity87% × 45%
Impact severity (EG Severity): CVSS 8.7 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.5% × 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
0.5%
EPSS %ILE
44th
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 (8.7): severity, escalated by confirmed exploitation. This CVE's 8.7 is its impact severity (EG Severity), not escalated.

EG Severity
8.7 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-29). 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

September 17, 2026

Last Modified

September 24, 2026

Advisory Details (4)

Auto-updated Sep 17, 2026
Patch available. Sources: github_commit, github_release, github, github_pr.
GitHub release Patch Available

v3.11.1

Patch available: ESP32Async/ESPAsyncWebServer v3.11.1

https://github.com/ESP32Async/ESPAsyncWebServer/releases/tag/v3.11.1
GitHub commit Patch Available

commit b928de7cbd7d (ESP32Async/ESPAsyncWebServer)

Patch available: ESP32Async/ESPAsyncWebServer v3.11.1 (contains commit b928de7cbd7d)

https://github.com/ESP32Async/ESPAsyncWebServer/commit/b928de7cbd7debcd6266ece6a6c46f10a86d3a6f
GitHub pull request Patch Available

Fix CWE-190 - DoS could happen with a specially crafted boundary parameter in a multipart request

Patch available: ESP32Async/ESPAsyncWebServer v3.11.1 (PR #445 merged 2026-06-08)

https://github.com/ESP32Async/ESPAsyncWebServer/pull/445
GitHub advisoryMentions a patch (unverified)

Integer overflow in multipart boundary parser causes denial of service · Advisory · ESP32Async/ESPAsyncWebServer · GitHub

https://github.com/ESP32Async/ESPAsyncWebServer/security/advisories/GHSA-4phx-fcj6-46r4

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 47× 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.

  1. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  2. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  3. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  4. 2026-10-30 14:20 UTCEG score recompute
  5. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  6. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  7. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  8. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  9. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  10. 2026-10-25 14:19 UTCEG score recompute
  11. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  12. 2026-10-23 21:17 UTCEG score recompute
  13. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  14. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  15. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  16. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  17. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  18. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  19. 2026-10-18 03:30 UTCEG score recompute
  20. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  21. 2026-10-17 04:10 UTCEG score recompute
  22. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  23. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  24. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  25. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
Show 52 more
  1. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  2. 2026-10-12 15:56 UTCEG score recompute
  3. 2026-10-11 19:39 UTCEG score recompute
  4. 2026-10-11 16:54 UTCEG score recompute
  5. 2026-10-11 14:17 UTCEG score recompute
  6. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  7. 2026-10-10 22:20 UTCEG score recompute
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  9. 2026-10-09 21:19 UTCEG score recompute
  10. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  11. 2026-10-08 20:26 UTCEG score recompute
  12. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  13. 2026-10-08 07:56 UTCEG score recompute
  14. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  15. 2026-10-06 18:38 UTCEG score recompute
  16. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  17. 2026-10-05 17:55 UTCEG score recompute
  18. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  19. 2026-10-05 05:35 UTCEG score recompute
  20. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  21. 2026-10-03 16:24 UTCEG score recompute
  22. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  23. 2026-10-03 04:00 UTCEG score recompute
  24. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  25. 2026-10-02 03:10 UTCEG score recompute
  26. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  27. 2026-10-01 02:17 UTCEG score recompute
  28. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  29. 2026-09-30 01:35 UTCEG score recompute
  30. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  31. 2026-09-29 00:53 UTCEG score recompute
  32. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  33. 2026-09-28 00:11 UTCEG score recompute
  34. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  35. 2026-09-26 23:29 UTCEG score recompute
  36. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  37. 2026-09-26 10:52 UTCEG score recompute
  38. 2026-09-24 21:35 UTCEG score recompute
  39. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  40. 2026-09-23 23:09 UTCEG score recompute
  41. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  42. 2026-09-22 22:01 UTCEG score recompute
  43. 2026-09-22 09:40 UTCEG score recompute
  44. 2026-09-21 21:17 UTCEG score recompute
  45. 2026-09-20 21:39 UTCEG score recompute
  46. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  47. 2026-09-19 20:54 UTCEG score recompute
  48. 2026-09-18 20:11 UTCEG score recompute
  49. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  50. 2026-09-17 19:26 UTCEG score recompute
  51. 2026-09-17 18:43 UTCEG score recomputeFirst assessed: 8.7 HIGH
  52. 2026-09-17 18:39 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-54571?
CVE-2026-54571 is a high-severity vulnerability; its CVE record was published on September 17, 2026. ESPAsyncWebServer is an asynchronous HTTP and WebSocket server library for ESP32, ESP8266, RP2040 and RP2350. Prior to 3.11.1, the multipart/form-data parser in src/WebRequest.cpp stores _boundaryPosition as an 8-bit value while _parseMultipartPostByte processes the boundary. A remote request…
When was the CVE record for CVE-2026-54571 published?
The CVE record for CVE-2026-54571 was published on September 17, 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 September 24, 2026; the record at its source may have been updated since.
Is CVE-2026-54571 actively exploited?
CVE-2026-54571 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (44th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-54571?
CVE-2026-54571 has a CVSS base score of 8.7 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-54571?
A fix for CVE-2026-54571 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

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