Libgcrypt up to 1.8.7/1.9.2 ElGamal Encryption timing discrepancy

CVSS Meta Temp Score
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CTI Interest Score
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5.0$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as problematic, was found in Libgcrypt up to 1.8.7/1.9.2. Affected is an unknown function of the component ElGamal Encryption. The manipulation results in timing discrepancy. This vulnerability is reported as CVE-2021-33560. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic has been found in Libgcrypt up to 1.8.7/1.9.2. Affected is some unknown functionality of the component ElGamal Encryption. The manipulation with an unknown input leads to a timing discrepancy vulnerability. CWE is classifying the issue as CWE-208. Two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not. This is going to have an impact on confidentiality. CVE summarizes:

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.

The weakness was disclosed 06/08/2021. The advisory is shared for download at dev.gnupg.org. This vulnerability is traded as CVE-2021-33560. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1592.

Upgrading to version 1.8.8 or 1.9.3 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at dev.gnupg.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.0
VulDB Meta Temp Score: 5.0

VulDB Base Score: 2.6
VulDB Temp Score: 2.5
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Timing discrepancy
CWE: CWE-208 / CWE-203 / CWE-200
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Libgcrypt 1.8.8/1.9.3
Patch: dev.gnupg.org

Timelineinfo

05/24/2021 🔍
06/08/2021 +15 days 🔍
06/08/2021 +0 days 🔍
12/03/2025 +1639 days 🔍

Sourcesinfo

Advisory: dev.gnupg.org
Status: Confirmed

CVE: CVE-2021-33560 (🔍)
GCVE (CVE): GCVE-0-2021-33560
GCVE (VulDB): GCVE-100-176472

Entryinfo

Created: 06/08/2021 15:01
Updated: 12/03/2025 17:08
Changes: 06/08/2021 15:01 (37), 06/10/2021 17:36 (5), 12/03/2025 17:08 (34)
Complete: 🔍
Cache ID: 216::103

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