CVE-2021-33560

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.

Published: 2021-06-08 Last update: 2025-12-03 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-33560 is rated Moderate Risk (51.8/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.43%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-33560

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-12-18 0.18% 0.43% +0.24%
2 2025-12-04 0.63% 0.18% -0.45%
3 2025-11-21 — 0.63% —

Full EPSS history (29 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-33560

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-33560

OS Trackers for CVE-2021-33560

vendor priority summary link
alpine — CVE-2021-33560: 1 source package rows (libgcrypt); 27 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 9, open 18. https://security.alpinelinux.org/vuln/CVE-2021-33560
debian not yet assigned CVE-2021-33560 not yet assigned priority: Debian including 1 source packages (libgcrypt20), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 4, open 1. https://security-tracker.debian.org/tracker/CVE-2021-33560
gentoo normal CVE-2021-33560: 1 GLSA(s) (202210-13), 1 atom(s) (dev-libs/libgcrypt); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-33560
redhat medium — https://access.redhat.com/security/cve/CVE-2021-33560
suse high CVE-2021-33560 severity important: SUSE including 446 source package names (0.1.0:libgcrypt20-1.8.2-8.39.1, 0.1.75:libgcrypt20-1.8.2-8.39.1, …), 696 product×package rows across 219 product lines (Container bci/bci-init, Container bci/bci-minimal, … (219 product lines)): Fixed 560, Known Affected 136. https://www.suse.com/security/cve/CVE-2021-33560/
ubuntu low CVE-2021-33560 low priority: Ubuntu including 1 source packages (libgcrypt20), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): released 14, DNE 1, ignored 1. https://ubuntu.com/security/CVE-2021-33560

Affected software / configurations for CVE-2021-33560

Vendor Product Version Raw CPE
gnupg libgcrypt < 1.8.8 cpe:2.3:a:gnupg:libgcrypt:*:*:*:*:*:*:*:*
gnupg libgcrypt >= 1.9.0, < 1.9.3 cpe:2.3:a:gnupg:libgcrypt:*:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
oracle communications_cloud_native_core_binding_support_function 1.11.0 cpe:2.3:a:oracle:communications_cloud_native_core_binding_support_function:1.11.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_network_function_cloud_native_environment 1.9.0 cpe:2.3:a:oracle:communications_cloud_native_core_network_function_cloud_native_environment:1.9.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_network_function_cloud_native_environment 1.10.0 cpe:2.3:a:oracle:communications_cloud_native_core_network_function_cloud_native_environment:1.10.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_network_repository_function 1.14.0 cpe:2.3:a:oracle:communications_cloud_native_core_network_repository_function:1.14.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_network_repository_function 1.15.0 cpe:2.3:a:oracle:communications_cloud_native_core_network_repository_function:1.15.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_network_repository_function 1.15.1 cpe:2.3:a:oracle:communications_cloud_native_core_network_repository_function:1.15.1:*:*:*:*:*:*:*
oracle communications_cloud_native_core_network_slice_selection_function 1.8.0 cpe:2.3:a:oracle:communications_cloud_native_core_network_slice_selection_function:1.8.0:*:*:*:*:*:*:*
oracle communications_cloud_native_core_service_communication_proxy 1.15.0 cpe:2.3:a:oracle:communications_cloud_native_core_service_communication_proxy:1.15.0:*:*:*:*:*:*:*

References for CVE-2021-33560

URL Tags
https://dev.gnupg.org/T5305 Release Notes Vendor Advisory
https://dev.gnupg.org/T5328 Vendor Advisory
https://dev.gnupg.org/T5466 Release Notes Vendor Advisory
https://dev.gnupg.org/rCe8b7f10be275bcedb5fc05ed4837a89bfd605c61 Patch Vendor Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00021.html Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BKKTOIGFW2SGN3DO2UHHVZ7MJSYN4AAB/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/R7OAPCUGPF3VLA7QAJUQSL255D4ITVTL/
https://security.gentoo.org/glsa/202210-13 Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.html Patch Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html Third Party Advisory
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