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CVE-2021-23840

7.5 · HIGH

Calls to EVP_CipherUpdate, EVP_EncryptUpdate and EVP_DecryptUpdate may overflow the output length argument in some cases where the input length is close to the maximum permissable length for an int…

Published Feb 16, 2021CWE-190EPSS 50.73%

Overview

CVE-2021-23840 is a high-severity vulnerability. It was published on February 16, 2021 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

Calls to EVP_CipherUpdate, EVP_EncryptUpdate and EVP_DecryptUpdate may overflow the output length argument in some cases where the input length is close to the maximum permissable length for an integer on the platform. In such cases the return value from the function call will be 1 (indicating success), but the output length value will be negative. This could cause applications to behave incorrectly or crash. OpenSSL versions 1.1.1i and below are affected by this issue. Users of these versions should upgrade to OpenSSL 1.1.1j. OpenSSL versions 1.0.2x and below are affected by this issue. However 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 1.1.1j (Affected 1.1.1-1.1.1i). Fixed in OpenSSL 1.0.2y (Affected 1.0.2-1.0.2x).

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refcert-portal.siemens.com/productcert/pdf/ssa-389290.pdfRefgit.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=6a51b9e1d0cf0bf8515f7201b68fb0a3482b3dc1Refgit.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=9b1129239f3ebb1d1c98ce9ed41d5c9476c47cb2Refkb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44846Refkc.mcafee.com/corporate/index?page=content&id=SB10366Reflists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3EReflists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3ERefsecurity.gentoo.org/glsa/202103-03Refsecurity.netapp.com/advisory/ntap-20210219-0009/Refsecurity.netapp.com/advisory/ntap-20240621-0006/

How CyberStrike helps

Frequently asked questions

What is CVE-2021-23840?

CVE-2021-23840 is a high-severity vulnerability. It was published on February 16, 2021 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2021-23840?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-23840?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-23840?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-23840 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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