An issue was discovered in Python before 3.8.18, 3.9.x before 3.9.18, 3.10.x before 3.10.13, and 3.11.x before 3.11.5. It primarily affects servers (such as HTTP servers) that use TLS client authentication. If a TLS server-side socket is created, receives data into the socket buffer, and then is closed quickly, there is a brief window where the SSLSocket instance will detect the socket as "not connected" and won't initiate a handshake, but buffered data will still be readable from the socket buffer. This data will not be authenticated if the server-side TLS peer is expecting client certificate authentication, and is indistinguishable from valid TLS stream data. Data is limited in size to the amount that will fit in the buffer. (The TLS connection cannot directly be used for data exfiltration because the vulnerable code path requires that the connection be closed on initialization of the SSLSocket.)
CVE-2023-40217
“—” beside the score: it is equal to NVD's CVSS score.
Score 5.3 from GitHub Security Advisory published 2023-08-25. NVD baseline CVSS 5.3; sources differ by 0.0.
Also known asEUVD-2023-44814 (ENISA EUVD) · GHSA-4j9r-82g6-9mj3 (GitHub Security Advisories)Source: ENISA EUVD
- Lower severity and no public exploit yet
A fix is available — apply it.
- CVSS v3
- 5.3
- EG Score
- 5.3MEDIUMmedium confidence
- EG Risk
- 39EG Risk 39/100
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)Severity53% × 45%Impact severity (EG Severity): CVSS 5.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.8% × 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
- 0.8%
- EPSS %ILE
- 56th
- 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 (5.3): severity, escalated by confirmed exploitation. This CVE's 5.3 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.8% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-25). 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
August 25, 2023
Last Modified
November 3, 2025
References (7)
- MITRE · CVE Programhttps://lists.debian.org/debian-lts-announce/2023/09/msg00022.html
- MITRE · CVE Programhttps://lists.debian.org/debian-lts-announce/2023/10/msg00017.html
- MITRE · CVE Programhttps://mail.python.org/archives/list/security-announce%40python.org/thread/PEPLII27KYHLF4AK3ZQGKYNCRERG4YXY/
- MITRE · CVE Programhttps://security.netapp.com/advisory/ntap-20231006-0014/
- MITRE · CVE Programhttps://www.python.org/dev/security/Vendor Advisory
- CVE Programhttps://lists.debian.org/debian-lts-announce/2024/11/msg00005.html
- CVE Programhttps://lists.debian.org/debian-lts-announce/2024/12/msg00000.html
Vendor Advisories for CVE-2023-40217(2)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2023:6793Red Hat Product SecurityHigh
Red Hat Security Advisory: rh-python38-python security update
- CVE-2023-40217Microsoft Security Response Center (MSRC)Medium
An issue was discovered in Python before 3.8.18 3.9.x before 3.9.18 3.10.x before 3.10.13 and 3.11.x before 3.11.5. It primarily affects servers (such as HTTP servers) that use TLS client authentication. If a TLS server-side socket is created receives data into the socket buffer and then is closed quickly there is a brief window where the SSLSocket instance will detect the socket as "not connected" and won't initiate a handshake but buffered data will still be readable from the socket buffer. This data will not be authenticated if the server-side TLS peer is expecting client certificate authentication and is indistinguishable from valid TLS stream data. Data is limited in size to the amount that will fit in the buffer. (The TLS connection cannot directly be used for data exfiltration because the vulnerable code path requires that the connection be closed on initialization of the SSLSocket.)
Patch Availability(25)
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(19 across 15 ecosystems)
Debian:11(3)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| pypy3 | 7.3.5+dfsg-2, 7.3.5+dfsg-2+deb11u1, 7.3.5+dfsg-2+deb11u2 |
| — |
| python2.7 | 2.7.18-8 |
| — |
| python3.9 | 3.9.2-1, 3.9.2-1+deb11u1 |
| — |
Debian:10(2)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python2.7 | 2.7.16-2, 2.7.16-2+deb10u1, 2.7.16-2+deb10u2 |
| — |
| python3.7 | 3.7.3-2 ... 3.7.3-2+deb10u5 (6 versions) |
| — |
Debian:12(2)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| pypy3 | 7.3.11+dfsg-2, 7.3.11+dfsg-2+deb12u1 |
| — |
| python3.11 | 3.11.2-6, 3.11.2-6+deb12u1 |
| — |
Alpine:v3.15(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python3 | — |
| — |
Alpine:v3.16(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python3 | — |
| — |
Alpine:v3.17(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python3 | — |
| — |
Alpine:v3.18(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python3 | — |
| — |
Alpine:v3.19(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python3 | — |
| — |
Alpine:v3.20(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python3 | — |
| — |
Alpine:v3.21(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python3 | — |
| — |
Alpine:v3.22(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python3 | — |
| — |
Alpine:v3.23(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python3 | — |
| — |
Alpine:v3.24(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python3 | — |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| pypy3 | — |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| pypy3 | — |
| — |
Additional Vendor Advisories
(23)
Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.
- Red HatRHSA-2023:5456IMPORTANT2023-08-25
RHSA-2023:5456 — Important
- Red HatRHSA-2023:5462IMPORTANT2023-08-25
RHSA-2023:5462 — Important
- Red HatRHSA-2023:5463IMPORTANT2023-08-25
RHSA-2023:5463 — Important
- Red HatRHSA-2023:5472IMPORTANT2023-08-25
RHSA-2023:5472 — Important
- Red HatRHSA-2023:5528IMPORTANT2023-08-25
RHSA-2023:5528 — Important
- Red HatRHSA-2023:5531IMPORTANT2023-08-25
RHSA-2023:5531 — Important
- Red HatRHSA-2023:5990IMPORTANT2023-08-25
RHSA-2023:5990 — Important
- Red HatRHSA-2023:5991IMPORTANT2023-08-25
RHSA-2023:5991 — Important
- Red HatRHSA-2023:5992IMPORTANT2023-08-25
RHSA-2023:5992 — Important
- Red HatRHSA-2023:5993IMPORTANT2023-08-25
RHSA-2023:5993 — Important
- Red HatRHSA-2023:5994IMPORTANT2023-08-25
RHSA-2023:5994 — Important
- Red HatRHSA-2023:5995IMPORTANT2023-08-25
RHSA-2023:5995 — Important
- Red HatRHSA-2023:5996IMPORTANT2023-08-25
RHSA-2023:5996 — Important
- Red HatRHSA-2023:5997IMPORTANT2023-08-25
RHSA-2023:5997 — Important
- Red HatRHSA-2023:5998IMPORTANT2023-08-25
RHSA-2023:5998 — Important
- Red HatRHSA-2023:6068IMPORTANT2023-08-25
RHSA-2023:6068 — Important
- Red HatRHSA-2023:6069IMPORTANT2023-08-25
RHSA-2023:6069 — Important
- Red HatRHSA-2023:6290IMPORTANT2023-08-25
RHSA-2023:6290 — Important
- Red HatRHSA-2023:6823IMPORTANT2023-08-25
RHSA-2023:6823 — Important
- Red HatRHSA-2023:6885IMPORTANT2023-08-25
RHSA-2023:6885 — Important
- UbuntuUSN-6513-1MEDIUM
Python vulnerabilities
- UbuntuUSN-6513-2MEDIUM
Python vulnerability
- UbuntuUSN-6891-1MEDIUM
Python vulnerabilities
Data Freshness Timeline
(refreshed 6× 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.
Showing the most recent 89 of 220 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. 11 repeat rows among the latest 100 are merged into the row they repeat. The 131 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-02 16:40 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-31 16:30 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-30 16:31 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-29 16:30 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-28 16:29 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-27 16:29 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-26 16:28 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-25 17:37 UTCEG score recompute
- 2026-10-25 16:29 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-24 16:29 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-24 13:47 UTCEG score recompute
- 2026-10-24 13:47 UTCVendor advisory
- 2026-10-24 13:47 UTCGHSA enrichmentGHSA-4j9r-82g6-9mj3 · GitHub CVSS 5.3
- 2026-10-23 16:29 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-22 16:31 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-21 16:29 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-20 16:30 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-19 16:29 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-18 16:29 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-18 07:54 UTCEG score recompute
- 2026-10-17 16:30 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-16 16:36 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-15 16:29 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-14 16:30 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-13 16:30 UTCEPSS rescoreEPSS 0.8% · 55th percentile
Show 64 moreShow fewer
- 2026-10-12 18:21 UTCEG score recompute
- 2026-10-12 16:31 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-11 21:47 UTCEG score recompute
- 2026-10-11 13:45 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-10 19:57 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-09 22:03 UTCOSV refresh
- 2026-10-09 20:05 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-08 17:06 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-07 23:46 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-06 15:15 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-10-05 17:41 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-10-04 23:20 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-10-03 14:23 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-10-01 19:48 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-30 16:28 UTCEG score recompute
- 2026-09-30 15:01 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-29 15:17 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-28 13:49 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-27 13:42 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-26 15:56 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-26 00:22 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-24 14:01 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-23 13:46 UTCEPSS rescoreEPSS 0.8% · 55th percentile
- 2026-09-20 20:14 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-20 06:13 UTCOSV refresh
- 2026-09-18 19:25 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-17 19:25 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-16 14:06 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-16 05:11 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-13 16:44 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-12 14:58 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-11 14:50 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-11 09:34 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-08 21:58 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-07 15:59 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-06 13:45 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-05 15:26 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-09-04 13:58 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-04 05:04 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-02 14:09 UTCEPSS rescoreEPSS 0.8% · 54th percentile
- 2026-09-01 13:51 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-09-01 09:59 UTCOSV refresh
- 2026-08-30 19:15 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-30 01:20 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-28 21:39 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-27 14:23 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-26 14:43 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-25 13:46 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-23 00:17 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-21 23:47 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-20 22:53 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-19 17:02 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-18 13:46 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-17 13:45 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-16 14:54 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-16 02:12 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-15 09:07 UTCOSV refresh
- 2026-08-15 01:28 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-13 21:58 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-12 13:48 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
- 2026-08-11 13:39 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
- 2026-08-09 13:44 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
- 2026-08-08 16:35 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
- 2026-08-07 16:25 UTCEPSS rescoreEPSS 0.8% · 52nd percentile
Related CVEs(same product + same vendor)
Same product
10 shownAlpine:v3.15:python3 · Debian:10:python3.7 · Alpine:v3.18:python3
Same vendor
10 shownredhat:RHSA-2023:6793 · ubuntu:USN-6891-1 · ubuntu:USN-6513-1
- CVE-2023-24329EG 7.5EPSS p98HIGH
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- CVE-2022-48566NVD 5.9EG 8.1HIGH
- CVE-2022-48560EG 7.5HIGH
- CVE-2022-45061EG 7.5HIGH
- CVE-2022-48564EG 6.5MEDIUM
- CVE-2015-20107NVD 7.6EG 9.8CRITICAL
- CVE-2021-29921EG 9.8EPSS p94CRITICAL
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- CVE-2020-27619EG 9.8EPSS p95CRITICAL
Frequently asked(5)
What is CVE-2023-40217?
When was the CVE record for CVE-2023-40217 published?
Is CVE-2023-40217 actively exploited?
What is the CVSS score of CVE-2023-40217?
How do I remediate CVE-2023-40217?
Dependency Blast Radius
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