CVE-2026-19445

CRITICALPre-NVD 9.29.2—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.2 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (34th 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 — 5 sources updated this week
9.2EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 9.2Exploit: None knownExposed services: Not assessed

An upstream fix is merged but not yet released — mitigate (WAF / firewall / segmentation) until the release ships, then apply it.

A remote, unauthenticated TLS client can make a server crash or call through a freed pointer if its sni_callback assigns a different context to SSLSocket.context (the documented way to select a certificate per server name) and nothing else keeps the original ssl.SSLContext alive. Typical cases are servers that create an SSLContext per connection or replace it while connections are open; servers that wrap their listening socket with it are not affected.

Mitigation: keep a reference to every SSLContext that sets sni_callback for the lifetime of the server. TLS clients are not affected.

CVSS v3
9.2
EG Score
9.2CRITICALmedium confidence
EG Risk
46
EG Risk 46/100CISA 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
Severity92% × 45%
Exploitation0% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track* or Attend at high (mission-essential systems).
Action: An upstream fix is merged but not yet in a tagged release. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high until it ships, then apply the release.
EPSS PROB
0.4%
EPSS %ILE
34th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* or Attend at high (mission-essential systems).

An upstream fix is merged but not yet in a tagged release. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high until it ships, then apply the release.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact total (CVSS ≥ 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
Upstream fix merged — awaiting tagged release. Sources: github_pr.
generic

Use-after-free for server-side SSLContext with sni_callback · Issue #156293 · python/cpython · GitHub

https://github.com/python/cpython/issues/156293
generic

Mailman 3 [CVE-2026-19445] Use-after-free of a server-side SSLContext when sni_callback switches contexts - Security-announce - python.org

https://mail.python.org/archives/list/[email protected]/thread/QMQIUQB6WGGC3MI7I3WKQXOYOBDSPPS3/
github_pr

gh-156293: Use-after-free for server-side SSLContext with sni_callback

Fix merged in python/cpython PR #158504 on 2026-09-30 — awaiting tagged release

https://github.com/python/cpython/pull/158504

Affected Packages

(12 across 7 ecosystems)
Debian:14(4)
PackageVulnerable rangeFix by version rangeDependents
pypy37.3.19+dfsg-2 ... 8.0.0+dfsg-1 (13 versions)
  • every version on: no fix on record
—
python3.133.13.11-1 ... 3.13.9-1 (9 versions)
  • every version on: no fix on record
—
python3.143.14.0-1 ... 3.14.8-1 (30 versions)
  • every version on: no fix on record
—
python3.153.15.0~a8-1 ... 3.15.0~rc2-3 (12 versions)
  • every version on: no fix on record
—
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
pypy37.3.11+dfsg-2 ... 8.0.0+dfsg-1 (31 versions)
  • every version on: no fix on record
—
python3.113.11.2-6 ... 3.11.9-1 (28 versions)
  • every version on: no fix on record
—
Debian:13(2)
PackageVulnerable rangeFix by version rangeDependents
pypy37.3.19+dfsg-2 ... 8.0.0+dfsg-1 (13 versions)
  • every version on: no fix on record
—
python3.133.13.11-1 ... 3.13.9-1 (14 versions)
  • every version on: no fix on record
—
Alpine:v3.21(1)
PackageVulnerable rangeFix by version rangeDependents
python3—
  • every version up to 3.12.15-r0: fixed in 3.12.15-r0
—
Alpine:v3.22(1)
PackageVulnerable rangeFix by version rangeDependents
python3—
  • every version up to 3.12.15-r0: fixed in 3.12.15-r0
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
python3—
  • every version up to 3.12.15-r0: fixed in 3.12.15-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
python3—
  • every version up to 3.14.8-r0: fixed in 3.14.8-r0
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 69× in last 7d / 69× 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. 2026-10-05 08:58 UTCVendor advisory
  2. 2026-10-05 08:58 UTCGHSA enrichment
  3. 2026-10-05 04:59 UTCVendor advisory
  4. 2026-10-05 04:59 UTCGHSA enrichment
  5. 2026-10-05 01:02 UTCEG score recompute
  6. 2026-10-05 01:02 UTCVendor advisory
  7. 2026-10-05 01:02 UTCGHSA enrichment
  8. 2026-10-04 23:21 UTCEPSS rescore
  9. 2026-10-04 21:01 UTCVendor advisory
  10. 2026-10-04 21:00 UTCGHSA enrichment
  11. 2026-10-04 17:02 UTCVendor advisory
  12. 2026-10-04 17:01 UTCGHSA enrichment
  13. 2026-10-04 13:04 UTCVendor advisory
  14. 2026-10-04 13:04 UTCGHSA enrichment
  15. 2026-10-04 09:03 UTCVendor advisory
  16. 2026-10-04 09:03 UTCGHSA enrichment
  17. 2026-10-04 05:05 UTCVendor advisory
  18. 2026-10-04 05:05 UTCGHSA enrichment
  19. 2026-10-04 01:09 UTCVendor advisory
  20. 2026-10-04 01:09 UTCGHSA enrichment
  21. 2026-10-03 21:12 UTCVendor advisory
  22. 2026-10-03 21:12 UTCGHSA enrichment
  23. 2026-10-03 17:14 UTCEG score recompute
  24. 2026-10-03 17:14 UTCVendor advisory
  25. 2026-10-03 17:14 UTCGHSA enrichment
Show 44 more
  1. 2026-10-03 13:16 UTCVendor advisory
  2. 2026-10-03 13:16 UTCGHSA enrichment
  3. 2026-10-03 09:19 UTCVendor advisory
  4. 2026-10-03 09:19 UTCGHSA enrichment
  5. 2026-10-03 05:20 UTCGHSA enrichment
  6. 2026-10-03 01:22 UTCEG score recompute
  7. 2026-10-03 01:22 UTCGHSA enrichment
  8. 2026-10-03 01:10 UTCEG score recompute
  9. 2026-10-03 01:10 UTCGHSA enrichment
  10. 2026-10-02 21:16 UTCGHSA enrichment
  11. 2026-10-02 17:18 UTCEG score recompute
  12. 2026-10-02 17:18 UTCGHSA enrichment
  13. 2026-10-02 13:19 UTCGHSA enrichment
  14. 2026-10-02 09:22 UTCGHSA enrichment
  15. 2026-10-02 05:25 UTCGHSA enrichment
  16. 2026-10-02 01:27 UTCEG score recompute
  17. 2026-10-02 01:26 UTCGHSA enrichment
  18. 2026-10-02 00:51 UTCEG score recompute
  19. 2026-10-02 00:51 UTCGHSA enrichment
  20. 2026-10-01 21:02 UTCEG score recompute
  21. 2026-10-01 21:02 UTCGHSA enrichment
  22. 2026-10-01 19:49 UTCEPSS rescore
  23. 2026-10-01 17:05 UTCGHSA enrichment
  24. 2026-10-01 13:08 UTCGHSA enrichment
  25. 2026-10-01 09:12 UTCGHSA enrichment
  26. 2026-10-01 05:15 UTCEG score recompute
  27. 2026-10-01 05:15 UTCGHSA enrichment
  28. 2026-10-01 01:18 UTCEG score recompute
  29. 2026-10-01 01:17 UTCGHSA enrichment
  30. 2026-09-30 23:31 UTCEG score recompute
  31. 2026-09-30 23:31 UTCGHSA enrichment
  32. 2026-09-30 22:46 UTCEG score recompute
  33. 2026-09-30 22:46 UTCGHSA enrichment
  34. 2026-09-30 21:28 UTCEG score recompute
  35. 2026-09-30 21:28 UTCGHSA enrichment
  36. 2026-09-30 21:01 UTCEG score recompute
  37. 2026-09-30 21:01 UTCGHSA enrichment
  38. 2026-09-30 19:25 UTCEG score recompute
  39. 2026-09-30 19:25 UTCGHSA enrichment
  40. 2026-09-30 19:12 UTCEG score recompute
  41. 2026-09-30 19:12 UTCGHSA enrichment
  42. 2026-09-30 17:25 UTCEG score recompute
  43. 2026-09-30 16:32 UTCEG score recompute
  44. 2026-09-30 16:31 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-19445?
CVE-2026-19445 is a critical vulnerability published on September 30, 2026. A remote, unauthenticated TLS client can make a server crash or call through a freed pointer if its sni_callback assigns a different context to SSLSocket.context (the documented way to select a certificate per server name) and nothing else keeps the original ssl.SSLContext alive. Typical cases are…
When was CVE-2026-19445 disclosed?
CVE-2026-19445 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-2026-19445 actively exploited?
CVE-2026-19445 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (34th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-19445?
CVE-2026-19445 has a CVSS base score of 9.2 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-19445?
An upstream fix for CVE-2026-19445 has been merged but is not yet in a tagged release. Until it ships, restrict network exposure of the affected system or apply the vendor's mitigation, then update to the release that contains the fix. The vendor advisories EchelonGraph has for CVE-2026-19445 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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