What’s Vulnerable › Vulnerabilities

CVE-2021-43527

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 17.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-12-08 · updated 2026-06-17
• Weakness: CWE-787

Description

NSS (Network Security Services) versions prior to 3.73 or 3.68.1 ESR are vulnerable to a heap overflow when handling DER-encoded DSA or RSA-PSS signatures. Applications using NSS for handling signatures encoded within CMS, S/MIME, PKCS \#7, or PKCS \#12 are likely to be impacted. Applications using NSS for certificate validation or other TLS, X.509, OCSP or CRL functionality may be impacted, depending on how they configure NSS. *Note: This vulnerability does NOT impact Mozilla Firefox.* However, email clients and PDF viewers that use NSS for signature verification, such as Thunderbird, LibreOffice, Evolution and Evince are believed to be impacted. This vulnerability affects NSS < 3.73 and NSS < 3.68.1.

Affected products

• Mozilla NSS: before 3.73 — fixed in 3.73
• Mozilla Nss Esr: before 3.68.1 — fixed in 3.68.1
• NetApp Cloud Backup: all versions
• E-Series SANtricity OS Controller Software 11.x: from 11.0 through 11.70.1
• Oracle Communications Cloud Native Core Binding Support Function: 1.11.0
• Oracle Communications Cloud Native Core Network Repository Function: 1.15.0, 1.15.1
• Oracle Communications Cloud Native Core Network Slice Selection Function: 1.8.0
• Oracle Corporation Communications Policy Management: 12.6.0.0.0
• Starwindsoftware Starwind San & Nas: v8r13
• Starwindsoftware Starwind Virtual San: v8r13-14398

How to fix

Upgrade to a fixed version: Mozilla NSS 3.73; Mozilla Nss Esr 3.68.1. Check the vendor advisory for mitigations.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=1737470
• https://cert-portal.siemens.com/productcert/pdf/ssa-594438.pdf
• https://ftp.mozilla.org/pub/security/nss/releases/NSS_3_68_1_RTM/
• https://ftp.mozilla.org/pub/security/nss/releases/NSS_3_73_RTM/
• https://security.gentoo.org/glsa/202212-05
• https://security.netapp.com/advisory/ntap-20211229-0002/
• https://www.mozilla.org/security/advisories/mfsa2021-51/
• https://www.oracle.com/security-alerts/cpuapr2022.html
• https://www.starwindsoftware.com/security/sw-20220802-0001/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1737470
• https://cert-portal.siemens.com/productcert/pdf/ssa-594438.pdf
• https://ftp.mozilla.org/pub/security/nss/releases/NSS_3_68_1_RTM/

Get alerted when CVE-2021-43527 or the next vulnerability affects your stack