VDB-182044 · CVE-2021-40528 · GCVE-0-2021-40528

Libgcrypt up to 1.9.3 ElGamal Encryption inadequate encryption

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
4.2	$0-$5k	0.00

Summaryinfo

A vulnerability, which was classified as problematic, was found in Libgcrypt up to 1.9.3. Impacted is an unknown function of the component ElGamal Encryption. Executing a manipulation can lead to inadequate encryption. The identification of this vulnerability is CVE-2021-40528. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Libgcrypt up to 1.9.3. This vulnerability affects some unknown functionality of the component ElGamal Encryption. The manipulation with an unknown input leads to a inadequate encryption vulnerability. The CWE definition for the vulnerability is CWE-326. The product stores or transmits sensitive data using an encryption scheme that is theoretically sound, but is not strong enough for the level of protection required. As an impact it is known to affect confidentiality. CVE summarizes:

The ElGamal implementation in Libgcrypt before 1.9.4 allows plaintext recovery because, during interaction between two cryptographic libraries, a certain dangerous combination of the prime defined by the receiver's public key, the generator defined by the receiver's public key, and the sender's ephemeral exponents can lead to a cross-configuration attack against OpenPGP.

The weakness was shared 09/07/2021. The advisory is shared for download at ibm.github.io. This vulnerability was named CVE-2021-40528. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1600.

Upgrading to version 1.9.4 eliminates this vulnerability. The upgrade is hosted for download at dev.gnupg.org. A possible mitigation has been published before and not just after the disclosure of the vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

Libgcrypt

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.2
VulDB Meta Temp Score: 4.2

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

NVD Base Score: 5.9
NVD Vector: 🔍

CVSSv2info

AV	AC	Au	C	I	A
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💳	💳	💳	💳	💳	💳
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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Inadequate encryption
CWE: CWE-326 / CWE-310
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Libgcrypt 1.9.4

Timelineinfo

08/22/2021 🔍
09/06/2021 +15 days 🔍
09/07/2021 +1 days 🔍
09/07/2021 +0 days 🔍
06/09/2025 +1371 days 🔍

Sourcesinfo

Advisory: ibm.github.io
Status: Confirmed

CVE: CVE-2021-40528 (🔍)
GCVE (CVE): GCVE-0-2021-40528
GCVE (VulDB): GCVE-100-182044

Entryinfo

Created: 09/07/2021 07:33
Updated: 06/09/2025 22:16
Changes: 09/07/2021 07:33 (54), 09/09/2021 22:16 (2), 09/09/2021 22:27 (1), 01/19/2023 23:57 (4), 06/09/2025 22:16 (33)
Complete: 🔍
Cache ID: 216::103