CVE & CISA-KEV Catalog

CVE-2021-40528

MEDIUM
5.9
CVSS v3
NVD

Description

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.

CWE-327

How to fix

Remediation Available
libgcrypt20Debian
Fixed in:1.8.7-6CVE-2021-40528
Fixed in:1.8.7-6CVE-2021-40528
Fixed in:1.8.7-6CVE-2021-40528
Fixed in:1.8.7-6CVE-2021-40528
libgcrypt20Ubuntu
Fixed in:1.6.5-2ubuntu0.6+esm1USN-5080-2
Fixed in:1.8.1-4ubuntu1.3USN-5080-1
Fixed in:1.8.5-5ubuntu1.1USN-5080-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredNone
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityHigh
IntegrityNone
AvailabilityNone

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Exploit Intelligence

1.42%probability of exploitation in 30 days
70thpercentile

Moderate risk: more likely to be exploited than 70% of all known CVEs.

References

Other references1
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Markdown

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HTML

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-06-09.