CVE-2021-23840

Integer overflow in CipherUpdate

Published Feb 16, 2021 CVSS 3.1 · 7.5 High EPSS 51.1% KEV · Not listed
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

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-2563-1 openssl security update
Debian DLA Debian DLA DLA-2565-1 openssl1.0 security update
Debian DSA Debian DSA DSA-4855-1 openssl security update
EUVD EUVD EUVD-2021-1843 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).
Github GHSA Github GHSA GHSA-qgm6-9472-pwq7 Integer Overflow in openssl-src
Ubuntu USN Ubuntu USN USN-4738-1 OpenSSL vulnerabilities
Ubuntu USN Ubuntu USN USN-5088-1 EDK II vulnerabilities
Ubuntu USN Ubuntu USN USN-7018-1 OpenSSL vulnerabilities
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
CPEs cpe:/a:redhat:acm:2.2::el7
Type Values Removed Values Added
CPEs cpe:/a:redhat:acm:2.2::el7
cpe:/a:redhat:acm:2.2::el8
Weaknesses

Sources

Status
PUBLISHED
Assigner
openssl
Published
Updated
Apr 16, 2026, 2:12 PM
Reserved
Jan 12, 2021, 12:00 AM
Status
Modified
Published
Feb 16, 2021, 5:15 PM
Modified
Jun 17, 2026, 3:38 AM
Severity
Moderate
Public date
Feb 16, 2021, 12:00 AM