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Fencer Vulns
high 7.5

CVE-2021-3580 json

A flaw was found in the way nettle's RSA decryption functions handled specially crafted ciphertext.

published 2021-08-05 5 y ago modified 2026-10-14 25 d ago also EUVD-2021-26889 , JLSEC-2026-576

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.7%
EPSS 2.7% chance of exploitation in 30 days, percentile 86%
public exploits
0
none known

Summary

A flaw was found in the way nettle's RSA decryption functions handled specially crafted ciphertext. An attacker could use this flaw to provide a manipulated ciphertext leading to application crash and denial of service.

Patch / fix

  • julia Nettle_jll 3.9.1+0
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • nettle Debian 14, Debian 13, Debian 12 3.7.3-1

debian advisories DEBIAN-CVE-2021-3580

  • nettle Ubuntu 18.04 LTS 3.4.1-0ubuntu0.18.04.1
  • nettle Ubuntu 20.04 LTS 3.5.1+really3.5.1-2ubuntu0.2

ubuntu advisories UBUNTU-CVE-2021-3580

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • gnutls RHEL 8 3.6.16-4.el8
  • nettle RHEL 8 3.4.1-7.el8
  • gnutls-c++ RHEL 8 3.6.16-4.el8
  • gnutls-dane RHEL 8 3.6.16-4.el8
  • gnutls-utils RHEL 8 3.6.16-4.el8

red hat advisories RHSA-2021:4451

  • libnettle SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +13 more 3.4.1-4.18.1
  • libnettle SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +11 more 2.7.1-13.6.1

suse advisories SUSE-SU-2021:2143-1SUSE-SU-2021:2135-1

  • libnettle openSUSE Leap 15.3 3.4.1-4.18.1
  • libnettle openSUSE Leap 15.2 3.4.1-lp152.4.6.1

opensuse advisories openSUSE-SU-2021:2143-1openSUSE-SU-2021:0906-1

  • gnutls AlmaLinux 8 3.6.16-4.el8
  • nettle AlmaLinux 8 3.4.1-7.el8
  • gnutls-c++ AlmaLinux 8 3.6.16-4.el8
  • gnutls-dane AlmaLinux 8 3.6.16-4.el8
  • gnutls-utils AlmaLinux 8 3.6.16-4.el8

almalinux advisories ALSA-2021:4451

  • gnutls Rocky Linux 8 3.6.16-4.el8
  • nettle Rocky Linux 8 3.4.1-7.el8

rocky linux advisories RLSA-2021:4451

  • nettle Alpine 3.12 3.5.1-r2
  • nettle Alpine 3.24, Alpine 3.23, Alpine 3.22 +9 more 3.7.3-r0

alpine advisories ALPINE-CVE-2021-3580

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • nettle CBL-Mariner 2.0 3.7.3-1

azure linux advisories AZL-6741

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

  • nettle Arch Linux 3.7.3-1

arch linux advisories AVG-2052

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-3580 updated cvss 7.5

nettle: Remote crash in RSA decryption via manipulated ciphertext

  • Red Hat Enterprise Linux 7 nettle
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux AppStream (v. 8) gnutls-c++ 3.6.16-4.el8, gnutls-dane 3.6.16-4.el8, gnutls-utils 3.6.16-4.el8 Red Hat Enterprise Linux BaseOS (v. 8) nettle 3.4.1-7.el8, gnutls 3.6.16-4.el8
    fixed: vendor fix RHSA-2021:4451
  • Red Hat Enterprise Linux 8 mingw-nettle, mingw32-nettle, mingw64-nettle Red Hat Enterprise Linux 9 nettle
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-23-348-10 updated cvss 7.5

Siemens SIMATIC S7-1500

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.0, < 3.1.5
    affected: fixed in V3.1.5, mitigation support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
23 mo ago

Exploit prediction

2.71% chance of exploitation in the next 30 days, higher than 86% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
julia Nettle_jll
<3.9.1+0
3.9.1+0

Affected products

  • n/a nettle
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.