CVE-2021-43527

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, data tampering, service disruption.

Exploit odds

17.6% chance of exploitation in the next 30 days (EPSS). Higher than most.

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-11-08 00:00 UTC ReservedThe CVE id was reserved by its CNA
2. 2021-12-08 22:15 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-06-17 04:11 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 17.6% in the next 30 days (EPSS).
• Severity: 9.8 CRITICAL (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-12-08 22:15 UTC

Last modified

2026-06-17 04:11 UTC

Exploit probability

17.6% · EPSS, next 30 days

Weakness

CWE-787 · Out-of-bounds write

Record status

Modified

Affected

• Mozilla Nss < 3.73
• Mozilla Nss Esr < 3.68.1
• Netapp Cloud Backup
• Netapp e-series Santricity Os Controller ≤ 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
• Oracle Communications Cloud Native Core Network Repository Function 1.15.1
• Oracle Communications Cloud Native Core Network Slice Selection Function 1.8.0

Attack profile CVSS 3.1 · 9.8

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-43527.md and follow it. Check whether this project is affected by CVE-2021-43527. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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