# CVE-2021-23840: libssl3t64: Calls to EVP_CipherUpdate, EVP_EncryptUpdate and EVP_DecryptUpdate mayoverflow the output length argument in some cas... CVE-2021-23840 is fixed in 17 products on 1 platform, first by libssl1.0.0 1.0.2n-1ubuntu5.6, released February 16, 2021. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2021-23840 - Priority: High - CVSS: 7.5 (Low) - EPSS: 0.5073 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Feb 16, 2021 ## Description Calls to EVP_CipherUpdate, EVP_EncryptUpdate and EVP_DecryptUpdate mayoverflow the output length argument in some cases where the input length isclose to the maximum permissable length for an integer on the platform. Insuch cases the return value from the function call will be 1 (indicatingsuccess), but the output length value will be negative. This could causeapplications to behave incorrectly or crash. OpenSSL versions 1.1.1i andbelow are affected by this issue. Users of these versions should upgrade toOpenSSL 1.1.1j. OpenSSL versions 1.0.2x and below are affected by thisissue. However OpenSSL 1.0.2 is out of support and no longer receivingpublic updates. Premium support customers of OpenSSL 1.0.2 should upgradeto 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). ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | edk2 rocky 8 | 0:20210527gite1999b264f1f-3.el8 | [RLSA-2021:4198](https://patchblox.com/security/data/fix/linux/rlsa-2021-4198.md) | Nov 9, 2021 | | Linux | edk2-aarch64 RHEL 8 | 0:20210527gite1999b264f1f-3.el8 | [RHSA-2021:4198](https://patchblox.com/security/data/fix/linux/rhsa-2021-4198.md) | Nov 9, 2021 | | Linux | edk2-ovmf RHEL 8 | 0:20210527gite1999b264f1f-3.el8 | [RHSA-2021:4198](https://patchblox.com/security/data/fix/linux/rhsa-2021-4198.md) | Nov 9, 2021 | | Linux | edk2-ovmf almalinux 8 | 20210527gite1999b264f1f-3.el8 | [ALSA-2021:4198](https://patchblox.com/security/data/fix/linux/alsa-2021-4198.md) | Nov 9, 2021 | | Linux | libssl1.0.0 Ubuntu 18.04.6 LTS (bionic) | 1.0.2n-1ubuntu5.6 | [libssl1.0.0 1.0.2n-1ubuntu5.6](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libssl1.0.0-1.0.2n-1ubuntu5.6.md) | Feb 16, 2021 | | Linux | libssl1.1 Ubuntu 18.04.6 LTS (bionic) | 1.1.1-1ubuntu2.1~18.04.8 | [libssl1.1 1.1.1-1ubuntu2.1~18.04.8](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libssl1.1-1.1.1-1ubuntu2.1-18.04.8.md) | Feb 16, 2021 | | Linux | libssl1.1 Ubuntu 20.04 LTS (focal) | 1.1.1f-1ubuntu2.2 | [libssl1.1 1.1.1f-1ubuntu2.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libssl1.1-1.1.1f-1ubuntu2.2.md) | Feb 16, 2021 | | Linux | libssl3t64 Ubuntu 24.10 (oracular) | 1.1.1j-1ubuntu1 | [libssl3t64 1.1.1j-1ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-libssl3t64-1.1.1j-1ubuntu1.md) | Jan 16, 2026 | | Linux | libssl3t64 Ubuntu 25.04 (plucky) | 1.1.1j-1ubuntu1 | [libssl3t64 1.1.1j-1ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-libssl3t64-1.1.1j-1ubuntu1.md) | Jan 16, 2026 | | Linux | openssl RHEL 8 | 1:1.1.1k-4.el8 | [RHSA-2021:4424](https://patchblox.com/security/data/fix/linux/rhsa-2021-4424.md) | Nov 9, 2021 | | Linux | openssl Ubuntu 18.04.6 LTS (bionic) | 1.1.1-1ubuntu2.1~18.04.8 | [openssl 1.1.1-1ubuntu2.1~18.04.8](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-openssl-1.1.1-1ubuntu2.1-18.04.8.md) | Feb 16, 2021 | | Linux | openssl Ubuntu 20.04 LTS (focal) | 1.1.1f-1ubuntu2.2 | [openssl 1.1.1f-1ubuntu2.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-openssl-1.1.1f-1ubuntu2.2.md) | Feb 16, 2021 | | Linux | openssl Ubuntu 24.10 (oracular) | 1.1.1j-1ubuntu1 | [openssl 1.1.1j-1ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-openssl-1.1.1j-1ubuntu1.md) | Jan 16, 2026 | | Linux | openssl Ubuntu 25.04 (plucky) | 1.1.1j-1ubuntu1 | [openssl 1.1.1j-1ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-openssl-1.1.1j-1ubuntu1.md) | Jan 16, 2026 | | Linux | openssl ol 8 | 2:1.1.1k-4.ksplice1.el8 | [ELSA-2021-9561](https://patchblox.com/security/data/fix/linux/elsa-2021-9561.md) | Nov 23, 2021 | | Linux | openssl rocky 8 | 1:1.1.1k-4.el8 | [RLSA-2021:4424](https://patchblox.com/security/data/fix/linux/rlsa-2021-4424.md) | Nov 9, 2021 | | Linux | openssl-debugsource ol 8 | 2:1.1.1k-4.ksplice1.el8 | [ELSA-2021-9561](https://patchblox.com/security/data/fix/linux/elsa-2021-9561.md) | Nov 23, 2021 | | Linux | openssl-devel RHEL 8 | 1:1.1.1k-4.el8 | [RHSA-2021:4424](https://patchblox.com/security/data/fix/linux/rhsa-2021-4424.md) | Nov 9, 2021 | | Linux | openssl-devel ol 8 | 2:1.1.1k-4.ksplice1.el8 | [ELSA-2021-9561](https://patchblox.com/security/data/fix/linux/elsa-2021-9561.md) | Nov 23, 2021 | | Linux | openssl-libs RHEL 8 | 1:1.1.1k-4.el8 | [RHSA-2021:4424](https://patchblox.com/security/data/fix/linux/rhsa-2021-4424.md) | Nov 9, 2021 | | Linux | openssl-libs ol 8 | 2:1.1.1k-4.ksplice1.el8 | [ELSA-2021-9561](https://patchblox.com/security/data/fix/linux/elsa-2021-9561.md) | Nov 23, 2021 | | Linux | openssl-perl RHEL 8 | 1:1.1.1k-4.el8 | [RHSA-2021:4424](https://patchblox.com/security/data/fix/linux/rhsa-2021-4424.md) | Nov 9, 2021 | | Linux | openssl-perl ol 8 | 2:1.1.1k-4.ksplice1.el8 | [ELSA-2021-9561](https://patchblox.com/security/data/fix/linux/elsa-2021-9561.md) | Nov 23, 2021 | | Linux | openssl-static ol 8 | 2:1.1.1k-4.ksplice1.el8 | [ELSA-2021-9561](https://patchblox.com/security/data/fix/linux/elsa-2021-9561.md) | Nov 23, 2021 | | Linux | openssl1.0 Ubuntu 18.04.6 LTS (bionic) | 1.0.2n-1ubuntu5.6 | [openssl1.0 1.0.2n-1ubuntu5.6](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-openssl1.0-1.0.2n-1ubuntu5.6.md) | Feb 16, 2021 | | Linux | ovmf Ubuntu 20.04 LTS (focal) | 0~20191122.bd85bf54-2ubuntu3.3 | [ovmf 0~20191122.bd85bf54-2ubuntu3.3](https://patchblox.com/security/data/fix/linux/ubuntu-focal-ovmf-0-20191122.bd85bf54-2ubuntu3.3.md) | Sep 13, 2021 | | Linux | qemu-efi Ubuntu 20.04 LTS (focal) | 0~20191122.bd85bf54-2ubuntu3.3 | [qemu-efi 0~20191122.bd85bf54-2ubuntu3.3](https://patchblox.com/security/data/fix/linux/ubuntu-focal-qemu-efi-0-20191122.bd85bf54-2ubuntu3.3.md) | Sep 13, 2021 | | Linux | qemu-efi-aarch64 Ubuntu 20.04 LTS (focal) | 0~20191122.bd85bf54-2ubuntu3.3 | [qemu-efi-aarch64 0~20191122.bd85bf54-2ubuntu3.3](https://patchblox.com/security/data/fix/linux/ubuntu-focal-qemu-efi-aarch64-0-20191122.bd85bf54-2ubuntu3.3.md) | Sep 13, 2021 | | Linux | qemu-efi-arm Ubuntu 20.04 LTS (focal) | 0~20191122.bd85bf54-2ubuntu3.3 | [qemu-efi-arm 0~20191122.bd85bf54-2ubuntu3.3](https://patchblox.com/security/data/fix/linux/ubuntu-focal-qemu-efi-arm-0-20191122.bd85bf54-2ubuntu3.3.md) | Sep 13, 2021 | --- Data as of 2026-11-08T19:12:23Z UTC. 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