Vulnerability-Lookup

BDU:2026-10550 (CVE-2026-2673)

Vulnerability from fstec – Published: 2026-07-27 – Updated: 2026-07-27 – View on bdu.fstec.ru Fixed

Title

Уязвимость инструмента для создания воспроизводимых и перемещаемых окружений Python relenv, связанная с выбором менее безопасного алгоритма в процессе согласования, позволяющая нарушителю выполнить атаку типа «человек посередине»

Summary

Уязвимость инструмента для создания воспроизводимых и перемещаемых окружений Python relenv связана с выбором менее безопасного алгоритма в процессе согласования. Эксплуатация уязвимости может позволить нарушителю, действующему удалённо, выполнить атаку типа «человек посередине»

Severity

6.4 (Medium) CVSS 2.0


                      
                        AV:N/AC:L/Au:N/C:N/I:P/A:P

6.5 (Medium) CVSS 3.1


                      
                        CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Class

Architecture vulnerability

Status

Confirmed by the vendor

Exploitation

Анализ целевого объекта

Incidents

Being clarified

Remediation

Software update

CWE

CWE-757 - Выбор менее безопасного алгоритма в процессе согласования («Algorithm Downgrade»)

Aliases

CVE-2026-2673

References

8 references

URL
http://www.openwall.com/lists/oss-security/2026/03/13/3
https://cert-portal.siemens.com/productcert/html/ssa-032379.html
https://github.com/advisories/GHSA-wj64-gh9j-xm82
https://github.com/openssl/openssl/commit/2157c9d81f7b0bd7dfa25b960e928ec28e8dd63f
https://github.com/openssl/openssl/commit/85977e013f32ceb96aa034c0e741adddc1a05e34
https://nvd.nist.gov/vuln/detail/CVE-2026-2673
https://openssl-library.org/news/secadv/20260313.txt
https://redos.red-soft.ru/search/?iblock_id=24&q=CVE-2026-2673

Impacted products

9 products from 6 vendors

Vendors

ООО «Ред Софт», Red Hat, Inc., Сообщество свободного программного обеспечения, Siemens AG, OpenSSL Software Foundation

Products

РЕД ОС (запись в едином реестре российских программ №3751), Red Hat Enterprise Linux, Debian GNU/Linux, Red Hat Hardened Images, SIMATIC CN 4100, relenv, OpenSSL, Red Hat JBoss Web Server, Red Hat JBoss Core Services

Versions

7.3 (РЕД ОС), 9 (Red Hat Enterprise Linux), 13 (Debian GNU/Linux), 8.0 (РЕД ОС), - (Red Hat Hardened Images), до 5.0 (SIMATIC CN 4100), до 0.22.14 (relenv), до 3.6.2 (OpenSSL), до 3.5.6 (OpenSSL), 7.0.0 (Red Hat JBoss Web Server), 6.2.4 (Red Hat JBoss Web Server), 2.4.62.SP4 (Red Hat JBoss Core Services)

Product types

Operating system, Application software, ПО программно-аппаратного средства АСУ ТП, Security software, Network device, Network software, Микропрограммный код аппаратных компонентов компьютера

Platforms

ООО «Ред Софт» РЕД ОС 7.3 (запись в едином реестре российских программ №3751), Red Hat, Inc. Red Hat Enterprise Linux 9, Сообщество свободного программного обеспечения Debian GNU/Linux 13, ООО «Ред Софт» РЕД ОС 8.0 (запись в едином реестре российских программ №3751)

Mitigations

Использование рекомендаций: https://github.com/advisories/GHSA-wj64-gh9j-xm82 Для Ред ОС: https://redos.red-soft.ru/search/?iblock_id=24&q=CVE-2026-2673 Для OpenSSL: https://openssl-library.org/news/secadv/20260313.txt Для Siemens AG: https://cert-portal.siemens.com/productcert/html/ssa-032379.html

JSON

To clipboard

{
  "CVSS 2.0": "AV:N/AC:L/Au:N/C:N/I:P/A:P",
  "CVSS 3.0": "AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L",
  "CVSS 4.0": null,
  "remediation_\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": null,
  "remediation_\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435": null,
  "\u0412\u0435\u043d\u0434\u043e\u0440 \u041f\u041e": "\u041e\u041e\u041e \u00ab\u0420\u0435\u0434 \u0421\u043e\u0444\u0442\u00bb, Red Hat, Inc., \u0421\u043e\u043e\u0431\u0449\u0435\u0441\u0442\u0432\u043e \u0441\u0432\u043e\u0431\u043e\u0434\u043d\u043e\u0433\u043e \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f, Siemens AG, OpenSSL Software Foundation",
  "\u0412\u0435\u0440\u0441\u0438\u044f \u041f\u041e": "7.3 (\u0420\u0415\u0414 \u041e\u0421), 9 (Red Hat Enterprise Linux), 13 (Debian GNU/Linux), 8.0 (\u0420\u0415\u0414 \u041e\u0421), - (Red Hat Hardened Images), \u0434\u043e 5.0 (SIMATIC CN 4100), \u0434\u043e 0.22.14 (relenv), \u0434\u043e 3.6.2 (OpenSSL), \u0434\u043e 3.5.6 (OpenSSL), 7.0.0 (Red Hat JBoss Web Server), 6.2.4 (Red Hat JBoss Web Server), 2.4.62.SP4 (Red Hat JBoss Core Services)",
  "\u0412\u043e\u0437\u043c\u043e\u0436\u043d\u044b\u0435 \u043c\u0435\u0440\u044b \u043f\u043e \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044e": "\u0418\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435 \u0440\u0435\u043a\u043e\u043c\u0435\u043d\u0434\u0430\u0446\u0438\u0439:\nhttps://github.com/advisories/GHSA-wj64-gh9j-xm82\n\n\u0414\u043b\u044f \u0420\u0435\u0434 \u041e\u0421:\nhttps://redos.red-soft.ru/search/?iblock_id=24\u0026q=CVE-2026-2673\n\n\u0414\u043b\u044f OpenSSL:\nhttps://openssl-library.org/news/secadv/20260313.txt\n\n\u0414\u043b\u044f Siemens AG:\nhttps://cert-portal.siemens.com/productcert/html/ssa-032379.html",
  "\u0414\u0430\u0442\u0430 \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0438\u044f": "13.03.2026",
  "\u0414\u0430\u0442\u0430 \u043f\u043e\u0441\u043b\u0435\u0434\u043d\u0435\u0433\u043e \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u044f": "27.07.2026",
  "\u0414\u0430\u0442\u0430 \u043f\u0443\u0431\u043b\u0438\u043a\u0430\u0446\u0438\u0438": "27.07.2026",
  "\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": "BDU:2026-10550",
  "\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440\u044b \u0434\u0440\u0443\u0433\u0438\u0445 \u0441\u0438\u0441\u0442\u0435\u043c \u043e\u043f\u0438\u0441\u0430\u043d\u0438\u0439 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "CVE-2026-2673",
  "\u0418\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044f \u043e\u0431 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430",
  "\u041a\u043b\u0430\u0441\u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0430\u0440\u0445\u0438\u0442\u0435\u043a\u0442\u0443\u0440\u044b",
  "\u041d\u0430\u0437\u0432\u0430\u043d\u0438\u0435 \u041f\u041e": "\u0420\u0415\u0414 \u041e\u0421 (\u0437\u0430\u043f\u0438\u0441\u044c \u0432 \u0435\u0434\u0438\u043d\u043e\u043c \u0440\u0435\u0435\u0441\u0442\u0440\u0435 \u0440\u043e\u0441\u0441\u0438\u0439\u0441\u043a\u0438\u0445 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c \u21163751), Red Hat Enterprise Linux, Debian GNU/Linux, Red Hat Hardened Images, SIMATIC CN 4100, relenv, OpenSSL, Red Hat JBoss Web Server, Red Hat JBoss Core Services",
  "\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u041e\u0421 \u0438 \u0442\u0438\u043f \u0430\u043f\u043f\u0430\u0440\u0430\u0442\u043d\u043e\u0439 \u043f\u043b\u0430\u0442\u0444\u043e\u0440\u043c\u044b": "\u041e\u041e\u041e \u00ab\u0420\u0435\u0434 \u0421\u043e\u0444\u0442\u00bb \u0420\u0415\u0414 \u041e\u0421 7.3  (\u0437\u0430\u043f\u0438\u0441\u044c \u0432 \u0435\u0434\u0438\u043d\u043e\u043c \u0440\u0435\u0435\u0441\u0442\u0440\u0435 \u0440\u043e\u0441\u0441\u0438\u0439\u0441\u043a\u0438\u0445 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c \u21163751), Red Hat, Inc. Red Hat Enterprise Linux 9 , \u0421\u043e\u043e\u0431\u0449\u0435\u0441\u0442\u0432\u043e \u0441\u0432\u043e\u0431\u043e\u0434\u043d\u043e\u0433\u043e \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f Debian GNU/Linux 13 , \u041e\u041e\u041e \u00ab\u0420\u0435\u0434 \u0421\u043e\u0444\u0442\u00bb \u0420\u0415\u0414 \u041e\u0421 8.0  (\u0437\u0430\u043f\u0438\u0441\u044c \u0432 \u0435\u0434\u0438\u043d\u043e\u043c \u0440\u0435\u0435\u0441\u0442\u0440\u0435 \u0440\u043e\u0441\u0441\u0438\u0439\u0441\u043a\u0438\u0445 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c \u21163751)",
  "\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0438\u043d\u0441\u0442\u0440\u0443\u043c\u0435\u043d\u0442\u0430 \u0434\u043b\u044f \u0441\u043e\u0437\u0434\u0430\u043d\u0438\u044f \u0432\u043e\u0441\u043f\u0440\u043e\u0438\u0437\u0432\u043e\u0434\u0438\u043c\u044b\u0445 \u0438 \u043f\u0435\u0440\u0435\u043c\u0435\u0449\u0430\u0435\u043c\u044b\u0445 \u043e\u043a\u0440\u0443\u0436\u0435\u043d\u0438\u0439 Python relenv, \u0441\u0432\u044f\u0437\u0430\u043d\u043d\u0430\u044f \u0441 \u0432\u044b\u0431\u043e\u0440\u043e\u043c \u043c\u0435\u043d\u0435\u0435 \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0433\u043e \u0430\u043b\u0433\u043e\u0440\u0438\u0442\u043c\u0430 \u0432 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u0435 \u0441\u043e\u0433\u043b\u0430\u0441\u043e\u0432\u0430\u043d\u0438\u044f, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043d\u0430\u0440\u0443\u0448\u0438\u0442\u0435\u043b\u044e \u0432\u044b\u043f\u043e\u043b\u043d\u0438\u0442\u044c \u0430\u0442\u0430\u043a\u0443 \u0442\u0438\u043f\u0430 \u00ab\u0447\u0435\u043b\u043e\u0432\u0435\u043a \u043f\u043e\u0441\u0435\u0440\u0435\u0434\u0438\u043d\u0435\u00bb",
  "\u041d\u0430\u043b\u0438\u0447\u0438\u0435 \u044d\u043a\u0441\u043f\u043b\u043e\u0439\u0442\u0430": "\u0414\u0430\u043d\u043d\u044b\u0435 \u0443\u0442\u043e\u0447\u043d\u044f\u044e\u0442\u0441\u044f",
  "\u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u043e\u0448\u0438\u0431\u043a\u0438 CWE": "\u0412\u044b\u0431\u043e\u0440 \u043c\u0435\u043d\u0435\u0435 \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0433\u043e \u0430\u043b\u0433\u043e\u0440\u0438\u0442\u043c\u0430 \u0432 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u0435 \u0441\u043e\u0433\u043b\u0430\u0441\u043e\u0432\u0430\u043d\u0438\u044f (\u00abAlgorithm Downgrade\u00bb) (CWE-757)",
  "\u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0438\u043d\u0441\u0442\u0440\u0443\u043c\u0435\u043d\u0442\u0430 \u0434\u043b\u044f \u0441\u043e\u0437\u0434\u0430\u043d\u0438\u044f \u0432\u043e\u0441\u043f\u0440\u043e\u0438\u0437\u0432\u043e\u0434\u0438\u043c\u044b\u0445 \u0438 \u043f\u0435\u0440\u0435\u043c\u0435\u0449\u0430\u0435\u043c\u044b\u0445 \u043e\u043a\u0440\u0443\u0436\u0435\u043d\u0438\u0439 Python relenv \u0441\u0432\u044f\u0437\u0430\u043d\u0430 \u0441 \u0432\u044b\u0431\u043e\u0440\u043e\u043c \u043c\u0435\u043d\u0435\u0435 \u0431\u0435\u0437\u043e\u043f\u0430\u0441\u043d\u043e\u0433\u043e \u0430\u043b\u0433\u043e\u0440\u0438\u0442\u043c\u0430 \u0432 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u0435 \u0441\u043e\u0433\u043b\u0430\u0441\u043e\u0432\u0430\u043d\u0438\u044f. \u042d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u043c\u043e\u0436\u0435\u0442 \u043f\u043e\u0437\u0432\u043e\u043b\u0438\u0442\u044c \u043d\u0430\u0440\u0443\u0448\u0438\u0442\u0435\u043b\u044e, \u0434\u0435\u0439\u0441\u0442\u0432\u0443\u044e\u0449\u0435\u043c\u0443 \u0443\u0434\u0430\u043b\u0451\u043d\u043d\u043e, \u0432\u044b\u043f\u043e\u043b\u043d\u0438\u0442\u044c \u0430\u0442\u0430\u043a\u0443 \u0442\u0438\u043f\u0430 \u00ab\u0447\u0435\u043b\u043e\u0432\u0435\u043a \u043f\u043e\u0441\u0435\u0440\u0435\u0434\u0438\u043d\u0435\u00bb",
  "\u041f\u043e\u0441\u043b\u0435\u0434\u0441\u0442\u0432\u0438\u044f \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": null,
  "\u041f\u0440\u043e\u0447\u0430\u044f \u0438\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044f": null,
  "\u0421\u0432\u044f\u0437\u044c \u0441 \u0438\u043d\u0446\u0438\u0434\u0435\u043d\u0442\u0430\u043c\u0438 \u0418\u0411": "\u0414\u0430\u043d\u043d\u044b\u0435 \u0443\u0442\u043e\u0447\u043d\u044f\u044e\u0442\u0441\u044f",
  "\u0421\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u041e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d\u0430",
  "\u0421\u043f\u043e\u0441\u043e\u0431 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044f": "\u041e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0435 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f",
  "\u0421\u043f\u043e\u0441\u043e\u0431 \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438": "\u0410\u043d\u0430\u043b\u0438\u0437 \u0446\u0435\u043b\u0435\u0432\u043e\u0433\u043e \u043e\u0431\u044a\u0435\u043a\u0442\u0430",
  "\u0421\u0441\u044b\u043b\u043a\u0438 \u043d\u0430 \u0438\u0441\u0442\u043e\u0447\u043d\u0438\u043a\u0438": "http://www.openwall.com/lists/oss-security/2026/03/13/3\nhttps://cert-portal.siemens.com/productcert/html/ssa-032379.html\nhttps://github.com/advisories/GHSA-wj64-gh9j-xm82\nhttps://github.com/openssl/openssl/commit/2157c9d81f7b0bd7dfa25b960e928ec28e8dd63f\nhttps://github.com/openssl/openssl/commit/85977e013f32ceb96aa034c0e741adddc1a05e34\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-2673\nhttps://openssl-library.org/news/secadv/20260313.txt\nhttps://redos.red-soft.ru/search/?iblock_id=24\u0026q=CVE-2026-2673",
  "\u0421\u0442\u0430\u0442\u0443\u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u041f\u043e\u0434\u0442\u0432\u0435\u0440\u0436\u0434\u0435\u043d\u0430 \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u0434\u0438\u0442\u0435\u043b\u0435\u043c",
  "\u0422\u0438\u043f \u041f\u041e": "\u041e\u043f\u0435\u0440\u0430\u0446\u0438\u043e\u043d\u043d\u0430\u044f \u0441\u0438\u0441\u0442\u0435\u043c\u0430, \u041f\u0440\u0438\u043a\u043b\u0430\u0434\u043d\u043e\u0435 \u041f\u041e \u0438\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u043e\u043d\u043d\u044b\u0445 \u0441\u0438\u0441\u0442\u0435\u043c, \u041f\u041e \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e-\u0430\u043f\u043f\u0430\u0440\u0430\u0442\u043d\u043e\u0433\u043e \u0441\u0440\u0435\u0434\u0441\u0442\u0432\u0430 \u0410\u0421\u0423 \u0422\u041f, \u041f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0435 \u0441\u0440\u0435\u0434\u0441\u0442\u0432\u043e \u0437\u0430\u0449\u0438\u0442\u044b, \u0421\u0435\u0442\u0435\u0432\u043e\u0435 \u0441\u0440\u0435\u0434\u0441\u0442\u0432\u043e, \u0421\u0435\u0442\u0435\u0432\u043e\u0435 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0435 \u0441\u0440\u0435\u0434\u0441\u0442\u0432\u043e, \u041c\u0438\u043a\u0440\u043e\u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u044b\u0439 \u043a\u043e\u0434 \u0430\u043f\u043f\u0430\u0440\u0430\u0442\u043d\u044b\u0445 \u043a\u043e\u043c\u043f\u043e\u043d\u0435\u043d\u0442\u043e\u0432 \u043a\u043e\u043c\u043f\u044c\u044e\u0442\u0435\u0440\u0430",
  "\u0422\u0438\u043f \u043e\u0448\u0438\u0431\u043a\u0438 CWE": "CWE-757",
  "\u0423\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0421\u0440\u0435\u0434\u043d\u0438\u0439 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (\u0431\u0430\u0437\u043e\u0432\u0430\u044f \u043e\u0446\u0435\u043d\u043a\u0430 CVSS 2.0 \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 6,4)\n\u0421\u0440\u0435\u0434\u043d\u0438\u0439 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (\u0431\u0430\u0437\u043e\u0432\u0430\u044f \u043e\u0446\u0435\u043d\u043a\u0430 CVSS 3.1 \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 6,5)"
}

CVE-2026-2673 (GCVE-0-2026-2673)

Vulnerability from cvelistv5 – Published: 2026-03-13 13:23 – Updated: 2026-05-18 19:23

Title

OpenSSL TLS 1.3 server may choose unexpected key agreement group

Summary

Issue summary: An OpenSSL TLS 1.3 server may fail to negotiate the expected preferred key exchange group when its key exchange group configuration includes the default by using the 'DEFAULT' keyword. Impact summary: A less preferred key exchange may be used even when a more preferred group is supported by both client and server, if the group was not included among the client's initial predicated keyshares. This will sometimes be the case with the new hybrid post-quantum groups, if the client chooses to defer their use until specifically requested by the server. If an OpenSSL TLS 1.3 server's configuration uses the 'DEFAULT' keyword to interpolate the built-in default group list into its own configuration, perhaps adding or removing specific elements, then an implementation defect causes the 'DEFAULT' list to lose its 'tuple' structure, and all server-supported groups were treated as a single sufficiently secure 'tuple', with the server not sending a Hello Retry Request (HRR) even when a group in a more preferred tuple was mutually supported. As a result, the client and server might fail to negotiate a mutually supported post-quantum key agreement group, such as 'X25519MLKEM768', if the client's configuration results in only 'classical' groups (such as 'X25519' being the only ones in the client's initial keyshare prediction). OpenSSL 3.5 and later support a new syntax for selecting the most preferred TLS 1.3 key agreement group on TLS servers. The old syntax had a single 'flat' list of groups, and treated all the supported groups as sufficiently secure. If any of the keyshares predicted by the client were supported by the server the most preferred among these was selected, even if other groups supported by the client, but not included in the list of predicted keyshares would have been more preferred, if included. The new syntax partitions the groups into distinct 'tuples' of roughly equivalent security. Within each tuple the most preferred group included among the client's predicted keyshares is chosen, but if the client supports a group from a more preferred tuple, but did not predict any corresponding keyshares, the server will ask the client to retry the ClientHello (by issuing a Hello Retry Request or HRR) with the most preferred mutually supported group. The above works as expected when the server's configuration uses the built-in default group list, or explicitly defines its own list by directly defining the various desired groups and group 'tuples'. No OpenSSL FIPS modules are affected by this issue, the code in question lies outside the FIPS boundary. OpenSSL 3.6 and 3.5 are vulnerable to this issue. OpenSSL 3.6 users should upgrade to OpenSSL 3.6.2 once it is released. OpenSSL 3.5 users should upgrade to OpenSSL 3.5.6 once it is released. OpenSSL 3.4, 3.3, 3.0, 1.0.2 and 1.1.1 are not affected by this issue.

Severity

6.5 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-03-17 17:17 UTC

CWE

CWE-757 - Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')

Assigner

openssl mitre root

References

5 references

URL	Tags
https://openssl-library.org/news/secadv/20260313.txt	vendor-advisory
https://github.com/openssl/openssl/commit/2157c9d…	patch
https://github.com/openssl/openssl/commit/85977e0…	patch
http://www.openwall.com/lists/oss-security/2026/03/13/3
https://cert-portal.siemens.com/productcert/html/…

Impacted products

2 products

Vendor	Product	Version
OpenSSL	OpenSSL	Affected: 3.6.0 , < 3.6.2 (semver) Affected: 3.5.0 , < 3.5.6 (semver)
Siemens	SIMATIC CN 4100	Affected: 0 , < V5.0 (custom)

Date Public

2026-03-13 14:00

Credits

Viktor Dukhovni Viktor Dukhovni

Show details on NVD website

JSON

To clipboard

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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

BDU:2026-10550 (CVE-2026-2673)

CVE-2026-2673 (GCVE-0-2026-2673)

Tags

Sightings

Nomenclature

Related by attack behaviour