CVE-2026-17084

MEDIUMPre-NVD 6.06.0—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.0 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 59% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 4 sources updated this week
6.0EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 6.0Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

The "stringprep" module didn't process characters from RFC 3454 tables B.2 or B.3 correctly: the latest Unicode codepoint attributes were used instead of the specified Unicode 3.2.0. This behavior would cause mismatches when processing domain names using IDNA 2003 (the "idna" codec) and the in_table_b2() function of the "stringprep" module. This only affects domain names containing characters that were not previously registered or had their Unicode attributes such as case-folding behavior updated since Unicode 3.2.0.

CVSS v3
6.0
EG Score
6.0(medium)
EG Risk
27(Track)
EG Risk 27/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity60% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
41%
KEV
Not listed

Published

August 18, 2026

Last Modified

August 19, 2026

Advisory Details (3)

Auto-updated Aug 18, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr.
generic

Mailman 3 [CVE-2026-17084] StringPrep algorithm considered Unicode codepoint attributes outside Unicode 3.2.0 - Security-announce - python.org

https://mail.python.org/archives/list/[email protected]/thread/EUHHTC6EV7HCLSUHP25C5VHSV4V2MUZN/
github_pr

gh-155292: Don't consider Unicode codepoint attributes outside RFC 3454

Fix merged in python/cpython PR #155293 on 2026-08-18 — awaiting tagged release

https://github.com/python/cpython/pull/155293
generic

stringprep and IDNA 2003 incorrectly handles some characters · Issue #155292 · python/cpython · GitHub

https://github.com/python/cpython/issues/155292

Vendor Advisories for CVE-2026-17084(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 20× in last 7d / 20× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-08-20 22:55 UTCEPSS rescore
  2. 2026-08-20 21:38 UTCGHSA enrichment
  3. 2026-08-19 23:29 UTCEG score recompute
  4. 2026-08-19 23:29 UTCGHSA enrichment
  5. 2026-08-19 17:03 UTCEPSS rescore
  6. 2026-08-19 01:20 UTCEG score recompute
  7. 2026-08-19 01:20 UTCGHSA enrichment
  8. 2026-08-19 00:31 UTCEG score recompute
  9. 2026-08-19 00:30 UTCGHSA enrichment
  10. 2026-08-18 18:25 UTCEG score recompute
  11. 2026-08-18 18:25 UTCGHSA enrichment
  12. 2026-08-18 17:18 UTCEG score recompute
  13. 2026-08-18 17:18 UTCGHSA enrichment
  14. 2026-08-18 16:37 UTCEG score recompute
  15. 2026-08-18 16:37 UTCGHSA enrichment
  16. 2026-08-18 16:13 UTCEG score recompute
  17. 2026-08-18 16:13 UTCGHSA enrichment
  18. 2026-08-18 14:44 UTCEG score recompute
  19. 2026-08-18 14:04 UTCEG score recompute
  20. 2026-08-18 14:00 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-17084?
CVE-2026-17084 is a medium vulnerability published on August 18, 2026. The "stringprep" module didn't process characters from RFC 3454 tables B.2 or B.3 correctly: the latest Unicode codepoint attributes were used instead of the specified Unicode 3.2.0. This behavior would cause mismatches when processing domain names using IDNA 2003 (the "idna" codec) and the…
When was CVE-2026-17084 disclosed?
CVE-2026-17084 was first published in the National Vulnerability Database on August 18, 2026, with the most recent update on August 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-17084 actively exploited?
CVE-2026-17084 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 58.5% of all scored CVEs.
What is the CVSS score of CVE-2026-17084?
CVE-2026-17084 has a CVSS v3 base score of 6.0 (NVD).
How do I remediate CVE-2026-17084?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-17084, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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