CVE-2026-27448

MEDIUMNVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.3 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 84% 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, nvd
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.3Exploit: None knownExposed: 0

A fix is available — apply it.

pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 0.14.0 and prior to version 26.0.0, if a user provided callback to set_tlsext_servername_callback raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it. Starting in version 26.0.0, unhandled exceptions now result in rejecting the connection.

CVSS v3
5.3
EG Score
5.3(medium)
EG Risk
24(Track)
EG Risk 24/100SSVC: 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
Severity53% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
16%
KEV
Not listed

Published

March 17, 2026

Last Modified

June 17, 2026

Advisory Details (3)

Auto-updated Aug 6, 2026
Patch available. Sources: github_commit, github.
github Patch Available

Unhandled exceptions in set_tlsext_servername_callback callbacks did not cancel connections · Advisory · pyca/pyopenssl · GitHub

https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424
github_commit

commit d41a814759a9 (pyca/pyopenssl)

Fix landed in pyca/pyopenssl commit d41a814759a9 — awaiting tagged release

https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0
generic

pyopenssl/CHANGELOG.rst at 358cbf29c4e364c59930e53a270116249581eaa3 · pyca/pyopenssl · GitHub

https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27

Vendor Advisories for CVE-2026-27448(2)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatpyopenssl-main-26.0.0-1.1.hum12026-04-09redhat

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)
PackageVulnerable rangeFixed inDependents
pyopenssl20.0.1-1 ... 26.4.0-1 (26 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
pyopenssl23.0.0-1 ... 26.4.0-1 (22 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
pyopenssl25.0.0-125.0.0-1+deb13u1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
pyopenssl25.0.0-1, 25.1.0-1, 25.1.0-2, 25.3.0-1, 25.3.0-226.0.0-1—
PyPI(1)
PackageVulnerable rangeFixed inDependents
pyopenssl0.14 ... 25.3.0 (33 versions)26.0.0—

Weakness Classification(1)

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

Additional Vendor Advisories

(2)

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 7× in last 7d / 27× 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. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 19:27 UTCEPSS rescore
  3. 2026-09-17 19:30 UTCEPSS rescore
  4. 2026-09-16 14:08 UTCEPSS rescore
  5. 2026-09-16 05:15 UTCEPSS rescore
  6. 2026-09-13 16:47 UTCEPSS rescore
  7. 2026-09-12 15:01 UTCEPSS rescore
  8. 2026-09-11 14:52 UTCEPSS rescore
  9. 2026-09-10 09:34 UTCEPSS rescore
  10. 2026-09-08 22:00 UTCEPSS rescore
  11. 2026-09-07 16:01 UTCEPSS rescore
  12. 2026-09-06 13:47 UTCEPSS rescore
  13. 2026-09-06 13:47 UTCEPSS rescore
  14. 2026-09-04 05:06 UTCEPSS rescore
  15. 2026-09-02 18:08 UTCOSV refresh
  16. 2026-09-02 14:11 UTCEPSS rescore
  17. 2026-09-01 13:53 UTCEPSS rescore
  18. 2026-09-01 04:39 UTCEPSS rescore
  19. 2026-08-30 19:17 UTCEPSS rescore
  20. 2026-08-30 01:22 UTCEPSS rescore
  21. 2026-08-28 21:41 UTCEPSS rescore
  22. 2026-08-27 14:25 UTCEPSS rescore
  23. 2026-08-26 14:46 UTCEPSS rescore
  24. 2026-08-25 13:48 UTCEPSS rescore
  25. 2026-08-23 00:19 UTCEPSS rescore
Show 45 more
  1. 2026-08-21 23:49 UTCEPSS rescore
  2. 2026-08-20 22:55 UTCEPSS rescore
  3. 2026-08-19 17:03 UTCEPSS rescore
  4. 2026-08-18 13:48 UTCEPSS rescore
  5. 2026-08-17 13:47 UTCEPSS rescore
  6. 2026-08-16 14:56 UTCEPSS rescore
  7. 2026-08-16 11:19 UTCEG score recompute
  8. 2026-08-16 11:19 UTCVendor advisory
  9. 2026-08-16 02:14 UTCEPSS rescore
  10. 2026-08-15 01:30 UTCEPSS rescore
  11. 2026-08-14 07:27 UTCEG score recompute
  12. 2026-08-14 07:27 UTCVendor advisory
  13. 2026-08-13 22:00 UTCEPSS rescore
  14. 2026-08-12 22:14 UTCEG score recompute
  15. 2026-08-12 22:14 UTCVendor advisory
  16. 2026-08-12 13:50 UTCEPSS rescore
  17. 2026-08-11 13:42 UTCEPSS rescore
  18. 2026-08-11 06:07 UTCEG score recompute
  19. 2026-08-11 06:07 UTCVendor advisory
  20. 2026-08-11 00:00 UTCEPSS rescore
  21. 2026-08-10 06:33 UTCEG score recompute
  22. 2026-08-10 06:33 UTCVendor advisory
  23. 2026-08-09 13:46 UTCEPSS rescore
  24. 2026-08-09 07:02 UTCEG score recompute
  25. 2026-08-09 07:02 UTCVendor advisory
  26. 2026-08-08 16:37 UTCEPSS rescore
  27. 2026-08-07 17:36 UTCEG score recompute
  28. 2026-08-07 17:36 UTCVendor advisory
  29. 2026-08-06 13:46 UTCEPSS rescore
  30. 2026-08-06 01:41 UTCEG score recompute
  31. 2026-08-06 01:41 UTCVendor advisory
  32. 2026-08-05 19:17 UTCEPSS rescore
  33. 2026-08-04 15:10 UTCEPSS rescore
  34. 2026-08-04 00:51 UTCEG score recompute
  35. 2026-08-04 00:51 UTCVendor advisory
  36. 2026-08-03 10:36 UTCEPSS rescore
  37. 2026-08-02 16:45 UTCEG score recompute▲ 3.60
  38. 2026-08-02 16:45 UTCVendor advisory
  39. 2026-08-02 02:26 UTCEPSS rescore
  40. 2026-07-30 16:27 UTCEPSS rescore
  41. 2026-07-30 01:30 UTCEPSS rescore
  42. 2026-07-28 15:36 UTCEPSS rescore
  43. 2026-07-27 12:52 UTCEG score recompute
  44. 2026-07-27 12:52 UTCVendor advisory
  45. 2026-07-27 12:50 UTCOSV refresh

Frequently asked(5)

What is CVE-2026-27448?
CVE-2026-27448 is a medium vulnerability published on March 17, 2026. pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 0.14.0 and prior to version 26.0.0, if a user provided callback to settlsextservername_callback raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for…
When was CVE-2026-27448 disclosed?
CVE-2026-27448 was first published in the National Vulnerability Database on March 17, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-27448 actively exploited?
CVE-2026-27448 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 84.4% of all scored CVEs.
What is the CVSS score of CVE-2026-27448?
CVE-2026-27448 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-27448?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-27448, 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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