libgcrypt: ElGamal implementation doesn't have semantic security due to incorrectly encoded plaintexts possibly allowing to obtain sensitive information
Published Feb 7, 2018
7.5
HIGHCVSS 3.0
EPSS 1.76%
Description
cipher/elgamal.c in Libgcrypt through 1.8.2, when used to encrypt messages directly, improperly encodes plaintexts, which allows attackers to obtain sensitive information by reading ciphertext data (i.e., it does not have semantic security in face of a ciphertext-only attack). The Decisional Diffie-Hellman (DDH) assumption does not hold for Libgcrypt's ElGamal implementation.
Affected products
No data.
No data.
Red Hat Enterprise Linux 5
libgcrypt
Not affected
Red Hat Enterprise Linux 6
libgcrypt
Not affected
Red Hat Enterprise Linux 7
libgcrypt
Not affected
Red Hat Enterprise Linux 8
libgcrypt
Not affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 5 | libgcrypt | Not affected | n/a |
| Red Hat Enterprise Linux 6 | libgcrypt | Not affected | n/a |
| Red Hat Enterprise Linux 7 | libgcrypt | Not affected | n/a |
| Red Hat Enterprise Linux 8 | libgcrypt | Not affected | n/a |
No package ranges for this CVE.
Remediation
Red Hat statement
This is not a security flaw in libgcrypt. However if an application uses The El-gamal algorithm implemented by libgcrypt in a particular way than the application would be vulnerable to security flaw(s). More detailed explanation is available at: https://lists.gnupg.org/pipermail/gcrypt-devel/2018-February/004401.html
Metrics
No CVSS v4.0 score for this CVE.
No CVSS v3.1 score for this CVE.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
1 other source (Red Hat) ▾
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
AV:N/AC:L/Au:N/C:P/I:N/A:N
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2021–2026- EPSS v1
- EPSS v5
- EPSS v2
- EPSS v3
Percentile over time
- EPSS v1
- EPSS v5
- EPSS v2
- EPSS v3
Table of values (9 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 1.76% (0.01762) | 77.20th | v5 (v2026.06.15) |
| Sep 20, 2026 | 1.76% (0.01762) | 77.02th | v5 (v2026.06.15) |
| Jul 20, 2024 | 0.19% (0.00193) | 57.26th | v3 (v2023.03.01) |
| Oct 27, 2023 | 0.19% (0.00193) | 56.90th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.19% (0.00191) | 54.89th | v3 (v2023.03.01) |
| Mar 6, 2023 | 1.02% (0.01018) | 40.69th | v2 (v2022.01.01) |
| Feb 4, 2022 | 1.02% (0.01018) | 19.50th | v2 (v2022.01.01) |
| Feb 3, 2022 | 1.04% (0.01040) | 28.32th | v5 (v2026.06.15) |
| Apr 14, 2021 | 1.04% (0.01040) | 0.00th | v1 |
References (8)
- https://access.redhat.com/security/cve/CVE-2018-6829 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1543437 Issue Tracking
- https://github.com/weikengchen/attack-on-libgcrypt-elgamal x_refsource_MISCThird Party Advisory
- https://github.com/weikengchen/attack-on-libgcrypt-elgamal/wiki x_refsource_MISCExploitThird Party Advisory
- https://lists.gnupg.org/pipermail/gcrypt-devel/2018-February/004394.html x_refsource_MISCIssue TrackingThird Party Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2018-6829
- https://www.cve.org/CVERecord?id=CVE-2018-6829
- https://www.oracle.com/security-alerts/cpujan2020.html x_refsource_MISC
| Link | Providers | Tags |
|---|---|---|
| https://access.redhat.com/security/cve/CVE-2018-6829 | Vendor Advisory | |
| https://bugzilla.redhat.com/show_bug.cgi?id=1543437 | Issue Tracking | |
| https://github.com/weikengchen/attack-on-libgcrypt-elgamal | x_refsource_MISCThird Party Advisory | |
| https://github.com/weikengchen/attack-on-libgcrypt-elgamal/wiki | x_refsource_MISCExploitThird Party Advisory | |
| https://lists.gnupg.org/pipermail/gcrypt-devel/2018-February/004394.html | x_refsource_MISCIssue TrackingThird Party Advisory | |
| https://nvd.nist.gov/vuln/detail/CVE-2018-6829 | ||
| https://www.cve.org/CVERecord?id=CVE-2018-6829 | ||
| https://www.oracle.com/security-alerts/cpujan2020.html | x_refsource_MISC |
Change history (0)
No recorded changes yet.