python-engineio is a Python implementation of the Engine.IO realtime client and server. Versions prior to 4.13.2 have two specific configurations of the python-engineio server in which the size of incoming messages is not checked before the messages are loaded into memory. An attacker can take advantage of these to cause unnecessary memory allocations in the python-engineio server. The two cases are POST requests, when using ASGI with the long polling transport and WebSocket messages, when using Aiohttp with the WebSocket transport. Version 4.13.2 addresses this issue. ASGI severs now only load the body of incoming requests into memory after the client is confirmed to be known and authenticated, and the payload size is below the maximum allowed size. Requests that do not comply with these requirements are discarded. Aiohttp servers configure the maximum payload size in the underlying WebSocket layer from Aiohttp, so that large messages are discarded by Aiohttp before they are delivered to python-engineio.
CVE-2026-48809
“—” 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: 0.5% (41st percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
Also known asEUVD-2026-56854 (ENISA EUVD) · GHSA-m9gh-vj53-gvh9 (GitHub Security Advisories)Source: ENISA EUVD
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 7.5
- EG Score
- 7.5HIGHmedium confidence
- EG Risk
- 49EG 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.Exploitation0.5% × 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
- 41st
- 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
- 0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). 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: 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.
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
June 26, 2026
Last Modified
September 18, 2026
Advisory Details (2)
Auto-updated Aug 11, 2026advisory-database/vulns/python-engineio/PYSEC-2026-3033.yaml at main · pypa/advisory-database · GitHub
https://github.com/pypa/advisory-database/tree/main/vulns/python-engineio/PYSEC-2026-3033.yamlPossible denial of service due to maximum payload size sometimes not being enforced · Advisory · miguelgrinberg/python-engineio · GitHub
https://github.com/miguelgrinberg/python-engineio/security/advisories/GHSA-m9gh-vj53-gvh9Vendor Advisories for CVE-2026-48809(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(4 across 4 ecosystems)
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python-engineio | 4.11.1-0.1 ... 4.9.0-2 (11 versions) |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python-engineio | 4.11.2-1 ... 4.14.0-1 (6 versions) |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python-engineio | 4.11.2-1, 4.12.1-1, 4.12.1-2, 4.13.0-1, 4.13.0-2 |
| — |
PyPI(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python-engineio | 0.1.0 ... 4.9.1 (143 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 37× 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.
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-10-25 14:23 UTCEG score recompute
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-10-23 20:01 UTCEG score recompute
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-18 03:34 UTCEG score recompute
- 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-17 12:14 UTCEG score recompute
- 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-13 20:54 UTCOSV refresh
- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-12 16:00 UTCEG score recompute
- 2026-10-11 19:43 UTCEG score recompute
- 2026-10-11 16:58 UTCEG score recompute
- 2026-10-11 14:22 UTCEG score recompute
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- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-26 00:27 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-09-23 07:48 UTCEG score recompute
- 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-09-18 20:36 UTCEG score recompute
- 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-09-18 07:11 UTCEG score recompute
- 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-09-14 01:00 UTCEG score recompute
- 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-09-12 15:33 UTCEG score recompute
- 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-09-06 15:01 UTCEG score recompute
- 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-30 19:20 UTCEG score recompute
- 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-27 23:01 UTCEG score recompute
- 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.3% · 19th percentile
- 2026-08-24 21:47 UTCEG score recompute
- 2026-08-23 08:31 UTCEG score recompute
- 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-08-22 09:24 UTCEG score recompute
- 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-08-21 05:08 UTCEG score recompute
- 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-08-20 06:44 UTCEG score recompute
- 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-08-18 23:42 UTCEG score recompute
- 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-08-17 00:26 UTCEG score recompute
- 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-08-16 13:17 UTCEG score recompute
- 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-08-15 03:50 UTCEG score recompute
- 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-08-14 05:31 UTCEG score recompute
- 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-08-12 18:39 UTCEG score recompute
- 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.3% · 20th percentile
- 2026-08-11 19:19 UTCEG score recompute
- 2026-07-30 11:33 UTCEG score recompute
- 2026-07-26 14:31 UTCEG score recompute
- 2026-07-23 03:18 UTCEG score recompute
- 2026-06-26 21:40 UTCEG score recompute
Related CVEs(same product + same CWE)
Same product
3 shownPyPI:python-engineio · Debian:12:python-engineio
Frequently asked(5)
What is CVE-2026-48809?
When was the CVE record for CVE-2026-48809 published?
Is CVE-2026-48809 actively exploited?
What is the CVSS score of CVE-2026-48809?
How do I remediate CVE-2026-48809?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-48809
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