4.3
CVSSv2

CVE-2021-23839

Published: 16/02/2021 Updated: 20/10/2021
CVSS v2 Base Score: 4.3 | Impact Score: 2.9 | Exploitability Score: 8.6
CVSS v3 Base Score: 3.7 | Impact Score: 1.4 | Exploitability Score: 2.2
Vector: AV:N/AC:M/Au:N/C:N/I:P/A:N

Vulnerability Summary

OpenSSL 1.0.2 supports SSLv2. If a client attempts to negotiate SSLv2 with a server that is configured to support both SSLv2 and more recent SSL and TLS versions then a check is made for a version rollback attack when unpadding an RSA signature. Clients that support SSL or TLS versions greater than SSLv2 are supposed to use a special form of padding. A server that supports greater than SSLv2 is supposed to reject connection attempts from a client where this special form of padding is present, because this indicates that a version rollback has occurred (i.e. both client and server support greater than SSLv2, and yet this is the version that is being requested). The implementation of this padding check inverted the logic so that the connection attempt is accepted if the padding is present, and rejected if it is absent. This means that such as server will accept a connection if a version rollback attack has occurred. Further the server will erroneously reject a connection if a normal SSLv2 connection attempt is made. Only OpenSSL 1.0.2 servers from version 1.0.2s to 1.0.2x are affected by this issue. In order to be vulnerable a 1.0.2 server must: 1) have configured SSLv2 support at compile time (this is off by default), 2) have configured SSLv2 support at runtime (this is off by default), 3) have configured SSLv2 ciphersuites (these are not in the default ciphersuite list) OpenSSL 1.1.1 does not have SSLv2 support and therefore is not vulnerable to this issue. The underlying error is in the implementation of the RSA_padding_check_SSLv23() function. This also affects the RSA_SSLV23_PADDING padding mode used by various other functions. Although 1.1.1 does not support SSLv2 the RSA_padding_check_SSLv23() function still exists, as does the RSA_SSLV23_PADDING padding mode. Applications that directly call that function or use that padding mode will encounter this issue. However since there is no support for the SSLv2 protocol in 1.1.1 this is considered a bug and not a security issue in that version. OpenSSL 1.0.2 is out of support and no longer receiving public updates. Premium support customers of OpenSSL 1.0.2 should upgrade to 1.0.2y. Other users should upgrade to 1.1.1j. Fixed in OpenSSL 1.0.2y (Affected 1.0.2s-1.0.2x).

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openssl openssl

oracle enterprise manager ops center 12.4.0.0

oracle graalvm 19.3.5

oracle graalvm 20.3.1.2

oracle graalvm 21.0.0.2

Vendor Advisories

IBM MQ for HP NonStop Server is affected by OpenSSL vulnerabilities CVE-2021-23839, CVE-2021-23840 and CVE-2021-23841 ...
OpenSSL 102 supports SSLv2 If a client attempts to negotiate SSLv2 with a server that is configured to support both SSLv2 and more recent SSL and TLS versions then a check is made for a version rollback attack when unpadding an RSA signature Clients that support SSL or TLS versions greater than SSLv2 are supposed to use a special form of paddin ...
IBM Connect:Direct for HP NonStop is affected by OpenSSL vulnerabilities CVE-2021-23839, CVE-2021-23840, and CVE-2021-23841 OpenSSL is vulnerable to a denial of service, caused by an integer overflow in CipherUpdate By sending an overly long argument, an attacker could exploit this vulnerability to cause the application to crash ...

Github Repositories

CVE-2021-23839 Exploit OpenSSL 102 supports SSLv2 If a client attempts to negotiate SSLv2 with a server that is configured to support both SSLv2 and more recent SSL and TLS versions then a check is made for a version rollback attack when unpadding an RSA signature Clients that support SSL or TLS versions greater than SSLv2 are supposed to use a special form of padding A se

Catlin Vulnerability Scanner This can be used to scan vulnerability in Tekton Tasks What is Trivy? Trivy (tri pronounced like trigger, vy pronounced like envy) is a simple and comprehensive vulnerability scanner for containers and other artifacts A software vulnerability is a glitch, flaw, or weakness present in the software or in an Operating System Trivy detects vulnerabi

TASSL-111k 新版本特性 1、基于开源openssl111k修改。相较于之前基于openssl111b版本的tassl,修复了以下漏洞: CVE-2019-1543 CVE-2019-1552 CVE-2019-1563 CVE-2019-1547 CVE-2019-1549 CVE-2020-1967 CVE-2020-1971 CVE-2021-23840 CVE-2021-23839 CVE-2021-23841 CVE-2021-3449 CVE-2021-3450 CVE-2021-3711 2、支持RFC 8998 ShangMi (SM) Cipher Suites for TLS