--- id: CVE-2021-33560 title: >- Libgcrypt before 1.8.8 and 1.9.x before 1.9.3 mishandles ElGamal encryption because it lacks exponent blinding to address a side-channel attack against mpi_powm, and the window size is not chosen appropriately summary: >- Libgcrypt before 1.8.8 and 1.9.x before 1.9.3 mishandles ElGamal encryption because it lacks exponent blinding to address a side-channel attack against mpi_powm, and the window size is not chosen appropriately. This, for example, affects… severity: high cvss: 7.5 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N' cwe: - CWE-203 - CWE-325 vendor: gnupg product: libgcrypt affected: - libgcrypt < 1.8.8 - 'libgcrypt >= 1.9.0, < 1.9.3' - debian_linux = 9.0 - fedora = 33 - fedora = 34 - communications_cloud_native_core_binding_support_function = 1.11.0 - >- communications_cloud_native_core_network_function_cloud_native_environment = 1.9.0 - >- communications_cloud_native_core_network_function_cloud_native_environment = 1.10.0 - communications_cloud_native_core_network_repository_function = 1.14.0 - communications_cloud_native_core_network_repository_function = 1.15.0 - communications_cloud_native_core_network_repository_function = 1.15.1 - communications_cloud_native_core_network_slice_selection_function = 1.8.0 - communications_cloud_native_core_service_communication_proxy = 1.15.0 patched: - libgcrypt 1.9.3 published: '2021-06-08' updated: '2026-10-14' sourceUpdated: '2026-10-14T12:17:12.267' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-33560' references: - url: 'https://dev.gnupg.org/T5305' label: cve@mitre.org - url: 'https://dev.gnupg.org/T5328' label: cve@mitre.org - url: 'https://dev.gnupg.org/T5466' label: cve@mitre.org - url: 'https://dev.gnupg.org/rCe8b7f10be275bcedb5fc05ed4837a89bfd605c61' label: cve@mitre.org - url: 'https://lists.debian.org/debian-lts-announce/2021/06/msg00021.html' label: cve@mitre.org - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BKKTOIGFW2SGN3DO2UHHVZ7MJSYN4AAB/ label: cve@mitre.org - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/R7OAPCUGPF3VLA7QAJUQSL255D4ITVTL/ label: cve@mitre.org - url: 'https://security.gentoo.org/glsa/202210-13' label: cve@mitre.org - url: 'https://www.oracle.com/security-alerts/cpuapr2022.html' label: cve@mitre.org - url: 'https://www.oracle.com/security-alerts/cpujan2022.html' label: cve@mitre.org - url: 'https://www.oracle.com/security-alerts/cpujul2022.html' label: cve@mitre.org - url: 'https://www.oracle.com/security-alerts/cpuoct2021.html' label: cve@mitre.org - url: 'https://dev.gnupg.org/T5305' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://dev.gnupg.org/T5328' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://dev.gnupg.org/T5466' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://dev.gnupg.org/rCe8b7f10be275bcedb5fc05ed4837a89bfd605c61' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://lists.debian.org/debian-lts-announce/2021/06/msg00021.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BKKTOIGFW2SGN3DO2UHHVZ7MJSYN4AAB/ label: af854a3a-2127-422b-91ae-364da2661108 - url: >- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/R7OAPCUGPF3VLA7QAJUQSL255D4ITVTL/ label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://security.gentoo.org/glsa/202210-13' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.oracle.com/security-alerts/cpuapr2022.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.oracle.com/security-alerts/cpujan2022.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.oracle.com/security-alerts/cpujul2022.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://www.oracle.com/security-alerts/cpuoct2021.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html' label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e tags: - nvd - exploit-available - cve.org epss: 0.02342 epssPercentile: 0.83198 exploits: github: 1 githubRepos: - 'https://github.com/IBM/PGP-client-checker-CVE-2021-33560' checkedAt: '2026-10-14T12:29:44.470Z' exploitAvailable: true ingestedAt: '2026-10-14T12:29:10.819Z' ssvc: exploitation: none automatable: 'yes' technicalImpact: partial timestamp: '2025-12-03T14:39:05.498424Z' --- ## Overview Libgcrypt before 1.8.8 and 1.9.x before 1.9.3 mishandles ElGamal encryption because it lacks exponent blinding to address a side-channel attack against mpi_powm, and the window size is not chosen appropriately. This, for example, affects use of ElGamal in OpenPGP. ## Affected - `libgcrypt < 1.8.8` - `libgcrypt >= 1.9.0, < 1.9.3` - `debian_linux = 9.0` - `fedora = 33` - `fedora = 34` - `communications_cloud_native_core_binding_support_function = 1.11.0` - `communications_cloud_native_core_network_function_cloud_native_environment = 1.9.0` - `communications_cloud_native_core_network_function_cloud_native_environment = 1.10.0` - `communications_cloud_native_core_network_repository_function = 1.14.0` - `communications_cloud_native_core_network_repository_function = 1.15.0` - `communications_cloud_native_core_network_repository_function = 1.15.1` - `communications_cloud_native_core_network_slice_selection_function = 1.8.0` - `communications_cloud_native_core_service_communication_proxy = 1.15.0` ## Remediation Upgrade past the affected range: - `libgcrypt 1.9.3`