CVE-2026-62966

HIGHPre-NVD 7.57.5
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (37th 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-2026-114469 (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: 0.4%CVSS: 7.5Exploit: 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 version 3.11.2, the multipart parser in src/WebRequest.cpp frees _itemBuffer and sets it to NULL when BOUNDARY_OR_DATA matches the closing boundary of a file part, before confirming the following terminator, while leaving _itemIsFile true. If the next byte is neither the final closing dashes nor a clean CRLF, the DASH3_OR_RETURN2 or EXPECT_FEED2 rewind branch re-injects provisionally consumed bytes through itemWriteByte. Because _itemIsFile remains true, _itemBuffer[_itemBufferIndex++] writes through a null pointer. On ESP32 this causes a StoreProhibited exception, panic and device reboot, producing remote denial of service. A route with a non-trivial body/upload handler, such as a file-upload or web-OTA endpoint, must be present. This issue is fixed in version 3.11.2.

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.
Exploitation0.4% × 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
0.4%
EPSS %ILE
37th
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.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-06). 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

October 30, 2026

Last Modified

November 6, 2026

Advisory Details (3)

Auto-updated Oct 30, 2026
Patch available. Sources: github, github_commit.
Web page

GitHub - ESP32Async/ESPAsyncWebServer at v3.11.2 · GitHub

https://github.com/ESP32Async/ESPAsyncWebServer/tree/v3.11.2
GitHub commit Patch Available

commit 4efbd35e597d (ESP32Async/ESPAsyncWebServer)

Patch available: ESP32Async/ESPAsyncWebServer v3.11.2 (contains commit 4efbd35e597d)

https://github.com/ESP32Async/ESPAsyncWebServer/commit/4efbd35e597d91f01749f2d4a14bb78fba8ea02e
GitHub advisoryMentions a patch (unverified)

Null-pointer write in ESPAsyncWebServer multipart parser · Advisory · ESP32Async/ESPAsyncWebServer · GitHub

https://github.com/ESP32Async/ESPAsyncWebServer/security/advisories/GHSA-8m8p-vhxc-jmjw

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 16× 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.

  1. 2026-11-13 16:53 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  2. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  3. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  4. 2026-11-10 16:45 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  5. 2026-11-09 16:35 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  6. 2026-11-08 16:40 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  7. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  8. 2026-11-06 19:27 UTCEchelonGraph re-scored
  9. 2026-11-06 18:27 UTCEchelonGraph re-scored
  10. 2026-11-06 16:39 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  11. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  12. 2026-11-04 16:36 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  13. 2026-11-03 16:48 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  14. 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  15. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  16. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  17. 2026-10-30 22:02 UTCENISA EUVD ID recordedEUVD-2026-114469 · Source: ENISA EUVD
  18. 2026-10-30 21:26 UTCEchelonGraph re-scored
  19. 2026-10-30 20:59 UTCEchelonGraph re-scoredFirst assessed: 7.5 HIGH
  20. 2026-10-30 20:58 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-62966?
CVE-2026-62966 is a high-severity vulnerability; its CVE record was published on October 30, 2026. ESPAsyncWebServer is an asynchronous HTTP and WebSocket server library for ESP32, ESP8266, RP2040 and RP2350. Prior to version 3.11.2, the multipart parser in src/WebRequest.cpp frees _itemBuffer and sets it to NULL when BOUNDARY_OR_DATA matches the closing boundary of a file part, before…
When was the CVE record for CVE-2026-62966 published?
The CVE record for CVE-2026-62966 was published on October 30, 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 November 6, 2026; the record at its source may have been updated since.
Is CVE-2026-62966 actively exploited?
CVE-2026-62966 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (37th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-62966?
CVE-2026-62966 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-62966?
A fix for CVE-2026-62966 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-62966

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