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Out-of-bounds Read Affecting openssl-libs package, versions <1:1.0.2k-23.el7_9

Severity

 Recommended
medium

Based on CentOS security rating.

Threat Intelligence

EPSS
0.49% (77th percentile)

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  • Snyk IDSNYK-CENTOS7-OPENSSLLIBS-2025480
  • published25 Aug 2021
  • disclosed24 Aug 2021
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Introduced: 24 Aug 2021

CVE-2021-3712  (opens in a new tab)
CWE-125  (opens in a new tab)

How to fix?

Upgrade Centos:7 openssl-libs to version 1:1.0.2k-23.el7_9 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream openssl-libs package and not the openssl-libs package as distributed by Centos. See How to fix? for Centos:7 relevant fixed versions and status.

ASN.1 strings are represented internally within OpenSSL as an ASN1_STRING structure which contains a buffer holding the string data and a field holding the buffer length. This contrasts with normal C strings which are repesented as a buffer for the string data which is terminated with a NUL (0) byte. Although not a strict requirement, ASN.1 strings that are parsed using OpenSSL's own "d2i" functions (and other similar parsing functions) as well as any string whose value has been set with the ASN1_STRING_set() function will additionally NUL terminate the byte array in the ASN1_STRING structure. However, it is possible for applications to directly construct valid ASN1_STRING structures which do not NUL terminate the byte array by directly setting the "data" and "length" fields in the ASN1_STRING array. This can also happen by using the ASN1_STRING_set0() function. Numerous OpenSSL functions that print ASN.1 data have been found to assume that the ASN1_STRING byte array will be NUL terminated, even though this is not guaranteed for strings that have been directly constructed. Where an application requests an ASN.1 structure to be printed, and where that ASN.1 structure contains ASN1_STRINGs that have been directly constructed by the application without NUL terminating the "data" field, then a read buffer overrun can occur. The same thing can also occur during name constraints processing of certificates (for example if a certificate has been directly constructed by the application instead of loading it via the OpenSSL parsing functions, and the certificate contains non NUL terminated ASN1_STRING structures). It can also occur in the X509_get1_email(), X509_REQ_get1_email() and X509_get1_ocsp() functions. If a malicious actor can cause an application to directly construct an ASN1_STRING and then process it through one of the affected OpenSSL functions then this issue could be hit. This might result in a crash (causing a Denial of Service attack). It could also result in the disclosure of private memory contents (such as private keys, or sensitive plaintext). Fixed in OpenSSL 1.1.1l (Affected 1.1.1-1.1.1k). Fixed in OpenSSL 1.0.2za (Affected 1.0.2-1.0.2y).

References

CVSS Scores

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