HOMEVULNERABILITIESCVE-2021-43527
CRITICAL

CVE-2021-43527

CWE-787Published: December 8, 2021· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2021-43527 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

From a weakness classification perspective (CWE-787): Out-of-bounds write vulnerabilities can lead to data corruption, crashes, or arbitrary code execution.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

Mozilla2 product(s)
nssnss esr
netapp2 product(s)
cloud backupe-series santricity os controller
Oracle4 product(s)
communications cloud native core binding support functioncommunications cloud native core network repository functioncommunications cloud native core network slice selection functioncommunications policy management
starwindsoftware2 product(s)
starwind san \& nasstarwind virtual san
Source: NVD CPE · 11 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

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

All References (18)

→
https://bugzilla.mozilla.org/show_bug.cgi?id=1737470Issue Tracking · Permissions Required · Vendor Advisory
→
https://cert-portal.siemens.com/productcert/pdf/ssa-594438.pdfThird Party Advisory
→
https://ftp.mozilla.org/pub/security/nss/releases/NSS_3_68_1_RTM/Vendor Advisory
→
https://ftp.mozilla.org/pub/security/nss/releases/NSS_3_73_RTM/Vendor Advisory
→
https://security.gentoo.org/glsa/202212-05Third Party Advisory
→
https://security.netapp.com/advisory/ntap-20211229-0002/Third Party Advisory
→
https://www.mozilla.org/security/advisories/mfsa2021-51/Vendor Advisory
→
https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch · Third Party Advisory
→
https://www.starwindsoftware.com/security/sw-20220802-0001/Third Party Advisory
→
https://bugzilla.mozilla.org/show_bug.cgi?id=1737470Issue Tracking · Permissions Required · Vendor Advisory
→
https://cert-portal.siemens.com/productcert/pdf/ssa-594438.pdfThird Party Advisory
→
https://ftp.mozilla.org/pub/security/nss/releases/NSS_3_68_1_RTM/Vendor Advisory
→
https://ftp.mozilla.org/pub/security/nss/releases/NSS_3_73_RTM/Vendor Advisory
→
https://security.gentoo.org/glsa/202212-05Third Party Advisory
→
https://security.netapp.com/advisory/ntap-20211229-0002/Third Party Advisory

Quick Facts

CVE IDCVE-2021-43527
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-787
CISA KEVNo
Affected4 vendor(s)
PublishedDec 8, 2021

Related CVEs (CWE-787)

CVE-2018-17160
10.0
CVE-2016-9343
10.0
CVE-2013-5610
10.0
CVE-2012-0751
10.0
CVE-2014-1478
10.0
CVE-2019-6235
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-43527 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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