CVE-2026-19553

HIGHPre-NVD 7.67.6—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.6 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (32nd percentile of EPSS-scored CVEs). 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 — Patch released this week
7.6EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 7.6Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

ssl.SSLContext.wrap_bio() didn't require the server_hostname argument to not be None if ssl.SSLContext.check_hostname was set. Due to a missing parameter check in SSLObject, if the server_hostname argument isn't supplied then hostname verification would be silently skipped.

This defect could lead to programs where certificate hostname verification *appeared* to be succeeding with SSLContext.check_hostname = True and no ValueError being raised due to misconfiguration.

If the program passes a server_hostname value that isn't an empty string or None to any of these APIs then certificate hostname verification proceeds as expected and the program is not affected by this vulnerability.

Mitigating this vulnerability doesn't require updating Python or applying the patch. To mitigate, pass a valid non-None and non-empty server_hostname value to SSLContext.wrap_bio(), asyncio.create_connection(), or asyncio.loop.start_tls() and certificate hostname verification will proceed as expected. Upgrading to the latest version of Python or applying the patch only changes the behavior from silently skipping hostname verification to raising a ValueError, similar to SSLContext.wrap_socket(), when server_hostname isn't supplied.

CVSS v3
7.6
EG Score
7.6HIGHmedium confidence
EG Risk
39
EG Risk 39/100CISA SSVC

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
Severity76% × 45%
Exploitation0% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
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
32nd
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track or 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 (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 30, 2026

Last Modified

October 3, 2026

Advisory Details (3)

Auto-updated Sep 30, 2026
Patch available. Sources: github_pr.
generic

Mailman 3 [CVE-2026-19553] SSLContext.wrap_bio() missing validation of server_hostname parameter - Security-announce - python.org

https://mail.python.org/archives/list/[email protected]/thread/QNZRG3YOAMTHDCMVCICXGY6YEFPY2VDL/
github_pr

gh-156793: Validate SSLContext.wrap_bio() parameters like wrap_socket()

Fix merged in python/cpython PR #158503 on 2026-09-30 — awaiting tagged release

https://github.com/python/cpython/pull/158503
generic

Validate SSLContext.wrap_bio() parameters like wrap_socket() · Issue #156793 · python/cpython · GitHub

https://github.com/python/cpython/issues/156793

Vendor Advisories for CVE-2026-19553(2)

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

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatpython3-14-main-3.14.7-1.3.hum12026-10-01redhat
redhatpython3-10-main-3.10.21-1.5.hum12026-10-01redhat
redhatpython3-11-main-3.11.16-1.5.hum12026-10-01redhat
redhatpython3-13-main-3.13.15-1.4.hum12026-10-01redhat
redhatpython3-12-main-3.12.14-1.4.hum12026-10-01redhat

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.

Weakness Classification(1)

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

Additional Vendor Advisories

(5)

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 42× in last 7d / 42× 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. 2026-10-04 00:31 UTCEG score recompute
  2. 2026-10-04 00:31 UTCVendor advisory
  3. 2026-10-04 00:31 UTCGHSA enrichment
  4. 2026-10-03 12:57 UTCVendor advisory
  5. 2026-10-03 12:57 UTCGHSA enrichment
  6. 2026-10-03 01:22 UTCEG score recompute
  7. 2026-10-03 01:22 UTCVendor advisory
  8. 2026-10-03 01:22 UTCGHSA enrichment
  9. 2026-10-03 01:10 UTCEG score recompute
  10. 2026-10-03 01:10 UTCVendor advisory
  11. 2026-10-03 01:10 UTCGHSA enrichment
  12. 2026-10-03 00:34 UTCEG score recompute
  13. 2026-10-03 00:34 UTCVendor advisory
  14. 2026-10-03 00:34 UTCGHSA enrichment
  15. 2026-10-02 13:00 UTCVendor advisory
  16. 2026-10-02 13:00 UTCGHSA enrichment
  17. 2026-10-02 01:26 UTCEG score recompute
  18. 2026-10-02 01:26 UTCGHSA enrichment
  19. 2026-10-02 00:51 UTCEG score recompute
  20. 2026-10-02 00:51 UTCGHSA enrichment
  21. 2026-10-02 00:26 UTCEG score recompute
  22. 2026-10-02 00:26 UTCGHSA enrichment
  23. 2026-10-01 19:49 UTCEPSS rescore
  24. 2026-10-01 12:51 UTCEG score recompute
  25. 2026-10-01 12:51 UTCGHSA enrichment
Show 17 more
  1. 2026-10-01 01:17 UTCEG score recompute
  2. 2026-10-01 01:17 UTCGHSA enrichment
  3. 2026-09-30 23:32 UTCEG score recompute
  4. 2026-09-30 23:31 UTCGHSA enrichment
  5. 2026-09-30 22:46 UTCEG score recompute
  6. 2026-09-30 22:46 UTCGHSA enrichment
  7. 2026-09-30 21:28 UTCEG score recompute
  8. 2026-09-30 21:28 UTCGHSA enrichment
  9. 2026-09-30 21:01 UTCEG score recompute
  10. 2026-09-30 21:01 UTCGHSA enrichment
  11. 2026-09-30 19:25 UTCEG score recompute
  12. 2026-09-30 19:25 UTCGHSA enrichment
  13. 2026-09-30 19:12 UTCEG score recompute
  14. 2026-09-30 19:12 UTCGHSA enrichment
  15. 2026-09-30 17:25 UTCEG score recompute
  16. 2026-09-30 16:32 UTCEG score recompute
  17. 2026-09-30 16:31 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-19553?
CVE-2026-19553 is a high vulnerability published on September 30, 2026. ssl.SSLContext.wrapbio() didn't require the serverhostname argument to not be None if ssl.SSLContext.check_hostname was set. Due to a missing parameter check in SSLObject, if the server_hostname argument isn't supplied then hostname verification would be silently skipped. This defect could lead to…
When was CVE-2026-19553 disclosed?
CVE-2026-19553 was first published on September 30, 2026, with the most recent update on October 3, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-19553 actively exploited?
CVE-2026-19553 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (32nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-19553?
CVE-2026-19553 has a CVSS base score of 7.6 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-19553?
A fix for CVE-2026-19553 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-19553 are linked in the Vendor Advisories panel on this page.

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