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Vulnerability details: VCID-tegv-r6ak-aaaa
Vulnerability ID VCID-tegv-r6ak-aaaa
Aliases CVE-2021-40528
Summary 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.
Status Published
Exploitability 0.5
Weighted Severity 6.2
Risk 3.1
Affected and Fixed Packages Package Details
Weaknesses (1)
CWE-327 Use of a Broken or Risky Cryptographic Algorithm
System Score Found at
generic_textual Medium http://people.canonical.com/~ubuntu-security/cve/2021/CVE-2021-40528.html
rhas Moderate https://access.redhat.com/errata/RHSA-2022:5311
cvssv3 5.9 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-40528.json
epss 0.00069 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
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epss 0.00094 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
epss 0.00094 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
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epss 0.00094 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
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epss 0.00094 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
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epss 0.00094 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
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epss 0.00166 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
epss 0.00199 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
epss 0.00199 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
epss 0.00199 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
epss 0.00199 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
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epss 0.00199 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
epss 0.00199 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
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epss 0.00199 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
epss 0.00251 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
epss 0.00251 https://api.first.org/data/v1/epss?cve=CVE-2021-40528
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rhbs medium https://bugzilla.redhat.com/show_bug.cgi?id=2002816
generic_textual Medium https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-40528
cvssv3.1 5.9 https://eprint.iacr.org/2021/923
generic_textual Medium https://eprint.iacr.org/2021/923
ssvc Track https://eprint.iacr.org/2021/923
cvssv3.1 5.9 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
cvssv3.1 5.9 https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git%3Ba=commit%3Bh=3462280f2e23e16adf3ed5176e0f2413d8861320
ssvc Track https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git%3Ba=commit%3Bh=3462280f2e23e16adf3ed5176e0f2413d8861320
cvssv3.1 5.9 https://ibm.github.io/system-security-research-updates/2021/07/20/insecurity-elgamal-pt1
generic_textual Medium https://ibm.github.io/system-security-research-updates/2021/07/20/insecurity-elgamal-pt1
ssvc Track https://ibm.github.io/system-security-research-updates/2021/07/20/insecurity-elgamal-pt1
cvssv3.1 5.9 https://ibm.github.io/system-security-research-updates/2021/09/06/insecurity-elgamal-pt2
generic_textual Medium https://ibm.github.io/system-security-research-updates/2021/09/06/insecurity-elgamal-pt2
ssvc Track https://ibm.github.io/system-security-research-updates/2021/09/06/insecurity-elgamal-pt2
cvssv2 2.6 https://nvd.nist.gov/vuln/detail/CVE-2021-40528
cvssv3 5.9 https://nvd.nist.gov/vuln/detail/CVE-2021-40528
cvssv3.1 5.9 https://nvd.nist.gov/vuln/detail/CVE-2021-40528
cvssv3.1 5.9 https://security.gentoo.org/glsa/202210-13
ssvc Track https://security.gentoo.org/glsa/202210-13
generic_textual Medium https://ubuntu.com/security/notices/USN-5080-1
generic_textual Medium https://ubuntu.com/security/notices/USN-5080-2
Reference id Reference type URL
http://people.canonical.com/~ubuntu-security/cve/2021/CVE-2021-40528.html
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-40528.json
https://api.first.org/data/v1/epss?cve=CVE-2021-40528
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-40528
https://eprint.iacr.org/2021/923
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git%3Ba=commit%3Bh=3462280f2e23e16adf3ed5176e0f2413d8861320
https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git;a=commit;h=3462280f2e23e16adf3ed5176e0f2413d8861320
https://ibm.github.io/system-security-research-updates/2021/07/20/insecurity-elgamal-pt1
https://ibm.github.io/system-security-research-updates/2021/09/06/insecurity-elgamal-pt2
https://security.gentoo.org/glsa/202210-13
https://ubuntu.com/security/notices/USN-5080-1
https://ubuntu.com/security/notices/USN-5080-2
2002816 https://bugzilla.redhat.com/show_bug.cgi?id=2002816
cpe:2.3:a:gnupg:libgcrypt:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:gnupg:libgcrypt:*:*:*:*:*:*:*:*
CVE-2021-40528 https://nvd.nist.gov/vuln/detail/CVE-2021-40528
RHSA-2022:5311 https://access.redhat.com/errata/RHSA-2022:5311
USN-5080-1 https://usn.ubuntu.com/5080-1/
USN-5080-2 https://usn.ubuntu.com/5080-2/
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-40528.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Found at https://eprint.iacr.org/2021/923
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2025-06-09T15:12:20Z/ Found at https://eprint.iacr.org/2021/923
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Found at https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Found at https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git%3Ba=commit%3Bh=3462280f2e23e16adf3ed5176e0f2413d8861320
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2025-06-09T15:12:20Z/ Found at https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git%3Ba=commit%3Bh=3462280f2e23e16adf3ed5176e0f2413d8861320
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Found at https://ibm.github.io/system-security-research-updates/2021/07/20/insecurity-elgamal-pt1
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2025-06-09T15:12:20Z/ Found at https://ibm.github.io/system-security-research-updates/2021/07/20/insecurity-elgamal-pt1
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Found at https://ibm.github.io/system-security-research-updates/2021/09/06/insecurity-elgamal-pt2
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2025-06-09T15:12:20Z/ Found at https://ibm.github.io/system-security-research-updates/2021/09/06/insecurity-elgamal-pt2
Vector: AV:N/AC:H/Au:N/C:P/I:N/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-40528
Exploitability (E) Access Vector (AV) Access Complexity (AC) Authentication (Au) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

high

functional

unproven

proof_of_concept

not_defined

local

adjacent_network

network

high

medium

low

multiple

single

none

none

partial

complete

none

partial

complete

none

partial

complete
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-40528
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-40528
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N Found at https://security.gentoo.org/glsa/202210-13
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2025-06-09T15:12:20Z/ Found at https://security.gentoo.org/glsa/202210-13
Exploit Prediction Scoring System (EPSS)
Percentile 0.18349
EPSS Score 0.00069
Published At March 28, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
There are no relevant records.