CVE-2026-27459

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 0.7%, top 49% 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
Trending — 3 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.8Exploit: None knownExposed: 0

A fix is available — apply it.

pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 22.0.0 and prior to version 26.0.0, if a user provided callback to set_cookie_generate_callback returned a cookie value greater than 256 bytes, pyOpenSSL would overflow an OpenSSL provided buffer. Starting in version 26.0.0, cookie values that are too long are now rejected.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
44(Track)
EG Risk 44/100SSVC: 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
Severity98% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
51%
KEV
Not listed

Published

March 18, 2026

Last Modified

August 21, 2026

Advisory Details (10)

Auto-updated Aug 21, 2026
Patch available. Sources: github, github_commit.
generic

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

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

commit 57f09bb4bb05 (pyca/pyopenssl)

Fix landed in pyca/pyopenssl commit 57f09bb4bb05 — awaiting tagged release

https://github.com/pyca/pyopenssl/commit/57f09bb4bb051d3bc2a1abd36e9525313d5cd408
github Patch Available

Buffer overflow if DTLS cookie callback returned too long of a value · Advisory · pyca/pyopenssl · GitHub

https://github.com/pyca/pyopenssl/security/advisories/GHSA-5pwr-322w-8jr4
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:13545
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:13512
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:13508
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:11996
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:11916
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:11856
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:10754

Vendor Advisories for CVE-2026-27459(20)

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

Patch Availability(19)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntupython3-openssl (25.0.0-1ubuntu0.1) @ questing2026-08-21ubuntu
redhatjaeger-main-2.20.0-0.8.hum12026-07-30redhat
redhatquay/quay-rhel9:17849872732026-07-29redhat
redhatquay/quay-rhel8:17808913952026-06-09redhat
redhatquay/quay-rhel9:17799222052026-06-02redhat
redhatquay/quay-rhel8:17796893922026-05-26redhat
redhatquay/quay-rhel9:17792040862026-05-19redhat
redhatpython3.12-pyOpenSSL-0:26.0.0-2.el9pc2026-05-07redhat
redhatpython-pyOpenSSL-0:25.1.0-0.3.el9pc2026-05-07redhat
redhatpython-pyOpenSSL-0:24.1.0-2.el9pc2026-05-07redhat
redhatansible-automation-platform-26/platform-resource-runner-rhel9:17773903332026-05-04redhat
redhatpython3.12-pyOpenSSL-0:26.0.0-1.el9ap2026-05-04redhat
redhatansible-automation-platform-25/lightspeed-rhel8:17774038722026-05-04redhat
redhatquay/quay-rhel8:17767823692026-04-30redhat
redhatquay/quay-rhel8:17767526462026-04-29redhat
redhatquay/quay-rhel8:17767369102026-04-29redhat
redhatpython-pyOpenSSL-0:24.1.0-2.el8ui2026-04-27redhat
redhatrhtas/model-transparency-rhel9:17758154072026-04-16redhat
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

(4 across 4 ecosystems)
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
pyopenssl22.0.0 ... 25.3.0 (15 versions)26.0.0—

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 24× in last 7d / 97× 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.

Showing the most recent 100 of 138 total refreshes for this CVE.

  1. 2026-08-21 12:32 UTCEG score recompute
  2. 2026-08-21 12:32 UTCVendor advisory
  3. 2026-08-20 22:55 UTCEPSS rescore
  4. 2026-08-20 13:59 UTCVendor advisory
  5. 2026-08-20 12:45 UTCEG score recompute
  6. 2026-08-20 12:45 UTCVendor advisory
  7. 2026-08-19 17:03 UTCEPSS rescore
  8. 2026-08-19 12:12 UTCEG score recompute
  9. 2026-08-19 12:12 UTCVendor advisory
  10. 2026-08-18 13:48 UTCEPSS rescore
  11. 2026-08-18 12:21 UTCEG score recompute
  12. 2026-08-18 12:21 UTCVendor advisory
  13. 2026-08-17 13:47 UTCEPSS rescore
  14. 2026-08-17 12:21 UTCVendor advisory
  15. 2026-08-17 12:13 UTCEG score recompute
  16. 2026-08-17 12:13 UTCVendor advisory
  17. 2026-08-16 14:56 UTCEPSS rescore
  18. 2026-08-16 11:19 UTCEG score recompute
  19. 2026-08-16 11:19 UTCVendor advisory
  20. 2026-08-16 02:14 UTCEPSS rescore
  21. 2026-08-15 01:30 UTCEPSS rescore
  22. 2026-08-15 00:02 UTCVendor advisory
  23. 2026-08-14 19:57 UTCVendor advisory
  24. 2026-08-14 15:36 UTCVendor advisory
  25. 2026-08-14 11:32 UTCVendor advisory
Show 75 more
  1. 2026-08-14 07:27 UTCEG score recompute
  2. 2026-08-14 07:27 UTCVendor advisory
  3. 2026-08-13 22:00 UTCEPSS rescore
  4. 2026-08-13 02:18 UTCVendor advisory
  5. 2026-08-12 22:14 UTCEG score recompute
  6. 2026-08-12 22:14 UTCVendor advisory
  7. 2026-08-12 13:50 UTCEPSS rescore
  8. 2026-08-12 12:39 UTCVendor advisory
  9. 2026-08-12 12:14 UTCVendor advisory
  10. 2026-08-12 01:38 UTCVendor advisory
  11. 2026-08-11 21:32 UTCEG score recompute
  12. 2026-08-11 21:32 UTCVendor advisory
  13. 2026-08-11 13:42 UTCEPSS rescore
  14. 2026-08-11 08:44 UTCVendor advisory
  15. 2026-08-11 04:39 UTCEG score recompute
  16. 2026-08-11 04:39 UTCVendor advisory
  17. 2026-08-11 00:00 UTCEPSS rescore
  18. 2026-08-10 12:15 UTCVendor advisory
  19. 2026-08-10 06:29 UTCVendor advisory
  20. 2026-08-10 02:04 UTCVendor advisory
  21. 2026-08-09 21:38 UTCVendor advisory
  22. 2026-08-09 17:34 UTCEG score recompute
  23. 2026-08-09 17:34 UTCVendor advisory
  24. 2026-08-09 13:46 UTCEPSS rescore
  25. 2026-08-09 13:24 UTCVendor advisory
  26. 2026-08-09 07:02 UTCEG score recompute
  27. 2026-08-09 07:02 UTCVendor advisory
  28. 2026-08-08 16:37 UTCEPSS rescore
  29. 2026-08-08 09:56 UTCVendor advisory
  30. 2026-08-08 05:51 UTCVendor advisory
  31. 2026-08-08 01:46 UTCVendor advisory
  32. 2026-08-07 21:41 UTCVendor advisory
  33. 2026-08-07 17:36 UTCEG score recompute
  34. 2026-08-07 17:36 UTCVendor advisory
  35. 2026-08-06 19:31 UTCEG score recompute
  36. 2026-08-06 19:31 UTCVendor advisory
  37. 2026-08-06 13:46 UTCEPSS rescore
  38. 2026-08-06 10:29 UTCVendor advisory
  39. 2026-08-06 05:46 UTCVendor advisory
  40. 2026-08-06 01:41 UTCEG score recompute
  41. 2026-08-06 01:41 UTCVendor advisory
  42. 2026-08-05 19:17 UTCEPSS rescore
  43. 2026-08-04 15:10 UTCEPSS rescore
  44. 2026-08-04 04:55 UTCVendor advisory
  45. 2026-08-04 00:50 UTCVendor advisory
  46. 2026-08-03 12:50 UTCEG score recompute
  47. 2026-08-03 12:50 UTCVendor advisory
  48. 2026-08-03 10:36 UTCEPSS rescore
  49. 2026-08-03 01:14 UTCVendor advisory
  50. 2026-08-02 20:50 UTCVendor advisory
  51. 2026-08-02 16:45 UTCEG score recompute
  52. 2026-08-02 16:45 UTCVendor advisory
  53. 2026-08-02 02:26 UTCEPSS rescore
  54. 2026-08-01 04:16 UTCEPSS rescore
  55. 2026-07-30 16:27 UTCEPSS rescore
  56. 2026-07-30 12:26 UTCVendor advisory
  57. 2026-07-30 12:09 UTCEG score recompute
  58. 2026-07-30 12:09 UTCVendor advisory
  59. 2026-07-30 01:30 UTCEPSS rescore
  60. 2026-07-28 15:36 UTCEPSS rescore
  61. 2026-07-27 12:41 UTCEG score recompute
  62. 2026-07-27 12:41 UTCVendor advisory
  63. 2026-07-26 14:54 UTCEPSS rescore
  64. 2026-07-26 14:54 UTCEPSS rescore
  65. 2026-07-25 14:18 UTCEPSS rescore
  66. 2026-07-25 14:17 UTCEPSS rescore
  67. 2026-07-24 14:17 UTCEPSS rescore
  68. 2026-07-23 14:18 UTCEPSS rescore
  69. 2026-07-23 14:18 UTCEPSS rescore
  70. 2026-07-23 03:08 UTCEG score recompute
  71. 2026-07-22 14:08 UTCEPSS rescore
  72. 2026-07-22 14:08 UTCEPSS rescore
  73. 2026-07-21 15:24 UTCEPSS rescore
  74. 2026-07-21 15:24 UTCEPSS rescore
  75. 2026-07-20 17:08 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-27459?
CVE-2026-27459 is a critical vulnerability published on March 18, 2026. pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 22.0.0 and prior to version 26.0.0, if a user provided callback to setcookiegenerate_callback returned a cookie value greater than 256 bytes, pyOpenSSL would overflow an OpenSSL provided buffer. Starting in version…
When was CVE-2026-27459 disclosed?
CVE-2026-27459 was first published in the National Vulnerability Database on March 18, 2026, with the most recent update on August 21, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-27459 actively exploited?
CVE-2026-27459 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 49.4% of all scored CVEs.
What is the CVSS score of CVE-2026-27459?
CVE-2026-27459 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-27459?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-27459, 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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