Internationalized Domain Names in Applications (IDNA) for Python provides support for Internationalized Domain Names in Applications (IDNA) and Unicode IDNA Compatibility Processing. In versions prior to 3.15, payloads such as "\u0660" * N or "\u30fb" * N + "\u6f22" utilize the valid_contexto function prior to length rejection, and for high values of N will take a long time to process. This is the same issue as CVE-2024-3651, however the original remediation in 2024 was not a complete fix. A specially crafted argument to the idna.encode() function could consume significant resources. This may lead to a denial-of-service. Starting in version 3.14, the function rejects long inputs as soon as practicable prior to any further processing to minimize resource consumption. In version 3.15, this approach was extended to lesser used alternate functions (i.e. per-label conversions and codec support). A workaround is available. Domain names cannot exceed 253 characters in length. If this length limit is enforced prior to passing the domain to the idna.encode() function, it should no longer consume significant resources. This is triggered by arbitrarily large inputs that would not occur in normal usage, but may be passed to the library assuming there is no preliminary input validation by the higher-level application.
CVE-2026-45409
“—” beside the score: it is equal to NVD's CVSS score.
Score 5.3 from GitHub Security Advisory (severity: MODERATE) published 2026-05-19. NVD baseline CVSS 5.3; sources differ by 0.0.
Also known asEUVD-2026-34921 (ENISA EUVD) · GHSA-65pc-fj4g-8rjx (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.Exploitation0.4% × 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
- 35th
- 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
- 0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). 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
May 19, 2026
Last Modified
July 23, 2026
Advisory Details (1)
Auto-updated Jun 14, 2026Specially crafted inputs to idna.encode() can bypass CVE-2024-3651 fix · Advisory · kjd/idna · GitHub
https://github.com/kjd/idna/security/advisories/GHSA-65pc-fj4g-8rjxVendor Advisories for CVE-2026-45409(12)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2026:66018Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Update Infrastructure 5.3 security update
- RHSA-2026:61783Red Hat Product SecurityHigh
Red Hat Security Advisory: A Subscription Management tool for finding and reporting Red Hat product usage
- RHSA-2026:58981Red Hat Product SecurityCritical
Red Hat Security Advisory: Red Hat Update Infrastructure 5.3 Technology Preview security update
- RHSA-2026:56431Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat OpenShift Data Foundation 4.18.27 security, enhancement & bug fix update
- RHSA-2026:54484Red Hat Product SecurityMedium
Red Hat Security Advisory: python-idna security update
- RHSA-2026:54481Red Hat Product SecurityMedium
Red Hat Security Advisory: python-idna security update
- RHSA-2026:54290Red Hat Product SecurityMedium
Red Hat Security Advisory: python-idna security update
- RHSA-2026:34119Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update
- +4 more
Patch Availability(12)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| ubuntu | python3-idna (3.11-1ubuntu0.1) @ resolute | 2026-10-22 | ubuntu |
| redhat | rhui5/rhua-rhel9:1788880581 | 2026-09-09 | redhat |
| redhat | discovery/discovery-ui-rhel9:1788206196 | 2026-08-31 | redhat |
| redhat | rhui5/rhua-tp-rhel9:1787241260 | 2026-08-24 | redhat |
| redhat | odf4/rook-ceph-rhel9-operator:1786706880 | 2026-08-18 | redhat |
| redhat | python-idna-0:2.10-8.el9_8 | 2026-08-13 | redhat |
| redhat | python-idna-0:3.7-6.el10_2 | 2026-08-13 | redhat |
| redhat | python-idna-0:2.5-8.el8_10 | 2026-08-12 | redhat |
| redhat | python-rpds-py-main-2026.6.3-1.hum1 | 2026-07-01 | redhat |
| redhat | python-idna-main-3.18-1.hum1 | 2026-06-12 | redhat |
| redhat | jaeger-main-2.19.0-1.hum1 | 2026-06-10 | redhat |
| pip | idna @ 3.15 (fixes < 3.15) | — | ghsa |
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
(5 across 5 ecosystems)
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python-idna | 2.10-1 ... 3.8-2 (16 versions) |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python-idna | 3.10-1 ... 3.8-2 (14 versions) |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python-idna | 3.10-1 |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| python-idna | 3.10-1, 3.11-1 |
| — |
PyPI(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| idna | 0.1 ... 3.9 (37 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Additional Vendor Advisories
(1)
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.
Data Freshness Timeline
(refreshed 9× in last 7d / 40× 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 100 of 194 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. None are among the latest 100 rows. The 94 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-02 16:45 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-11-01 07:48 UTCGHSA enrichmentGHSA-65pc-fj4g-8rjx · GitHub severity MODERATE · GitHub CVSS 5.3
- 2026-11-01 07:48 UTCEG score recompute
- 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.4% · 35th percentile
- 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-10-25 14:26 UTCEG score recompute
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-22 23:35 UTCEG score recompute
- 2026-10-22 23:35 UTCVendor advisory
- 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-18 03:38 UTCEG score recompute
- 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
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- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-10-12 16:04 UTCEG score recompute
- 2026-10-11 19:46 UTCEG score recompute
- 2026-10-11 17:01 UTCEG score recompute
- 2026-10-11 14:26 UTCEG score recompute
- 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.5% · 37th percentile
- 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-23 17:05 UTCEG score recompute
- 2026-08-23 17:05 UTCVendor advisory
- 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-21 23:38 UTCEG score recompute
- 2026-08-21 23:38 UTCVendor advisory
- 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-20 19:02 UTCEG score recompute
- 2026-08-20 19:02 UTCVendor advisory
- 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-17 10:00 UTCEG score recompute
- 2026-08-17 10:00 UTCVendor advisory
- 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-16 03:35 UTCEG score recompute
- 2026-08-16 03:35 UTCVendor advisory
- 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.4% · 34th percentile
- 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-15 00:11 UTCVendor advisory
- 2026-08-14 02:07 UTCEG score recompute
- 2026-08-14 02:07 UTCVendor advisory
- 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-12 20:59 UTCEG score recompute
- 2026-08-12 20:59 UTCVendor advisory
- 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-11 22:55 UTCEG score recompute
- 2026-08-11 22:55 UTCVendor advisory
- 2026-08-11 00:39 UTCEG score recompute
- 2026-08-11 00:39 UTCVendor advisory
- 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.4% · 33rd percentile
- 2026-08-09 23:41 UTCEG score recompute
Related CVEs(same product + same vendor + same CWE)
Same vendor
10 shownredhat:RHSA-2026:58981
Frequently asked(5)
What is CVE-2026-45409?
When was the CVE record for CVE-2026-45409 published?
Is CVE-2026-45409 actively exploited?
What is the CVSS score of CVE-2026-45409?
How do I remediate CVE-2026-45409?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-45409
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