UBUNTU-CVE-2021-23841

    Dashboard / Vulnerabilities / UBUNTU-CVE-2021-23841

    UBUNTU-CVE-2021-23841

    Published: 16 Feb 2021Last Modified: 22 Apr 2026

    Summary:

    Details: The OpenSSL public API function X509_issuer_and_serial_hash() attempts to create a unique hash value based on the issuer and serial number data contained within an X509 certificate. However it fails to correctly handle any errors that may occur while parsing the issuer field (which might occur if the issuer field is maliciously constructed). This may subsequently result in a NULL pointer deref and a crash leading to a potential denial of service attack. The function X509_issuer_and_serial_hash() is never directly called by OpenSSL itself so applications are only vulnerable if they use this function directly and they use it on certificates that may have been obtained from untrusted sources. 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).

    Affected packages

    Package

    Name: openssl

    Purl: pkg:deb/ubuntu/[email protected]+esm2?arch=source&distro=trusty/esm

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -1.0.1f-1ubuntu2.27+esm2

    Affected versions

    1.0.1e-3ubuntu1
    1.0.1e-4ubuntu1
    1.0.1e-4ubuntu2
    1.0.1e-4ubuntu3
    1.0.1e-4ubuntu4
    1.0.1f-1ubuntu1
    1.0.1f-1ubuntu2
    1.0.1f-1ubuntu2.1
    1.0.1f-1ubuntu2.2
    1.0.1f-1ubuntu2.3
    1.0.1f-1ubuntu2.4
    1.0.1f-1ubuntu2.5
    1.0.1f-1ubuntu2.7
    1.0.1f-1ubuntu2.8
    1.0.1f-1ubuntu2.11
    1.0.1f-1ubuntu2.12
    1.0.1f-1ubuntu2.15
    1.0.1f-1ubuntu2.16
    1.0.1f-1ubuntu2.17
    1.0.1f-1ubuntu2.18
    1.0.1f-1ubuntu2.19
    1.0.1f-1ubuntu2.20
    1.0.1f-1ubuntu2.21
    1.0.1f-1ubuntu2.22
    1.0.1f-1ubuntu2.23
    1.0.1f-1ubuntu2.24
    1.0.1f-1ubuntu2.25
    1.0.1f-1ubuntu2.26
    1.0.1f-1ubuntu2.27
    1.0.1f-1ubuntu2.27+esm1

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    UBUNTU-CVE-2021-23841 | CVE-DB