How severe is CVE-2021-43568?

CVE-2021-43568 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-43568 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-43568?

CVE-2021-43568 affects Starkbank Elixir Ecdsa. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-43568?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-43568 published?

CVE-2021-43568 was published on 2021-11-09 and last updated on 2026-06-17.

CVE-2021-43568

CVE-2021-43568 is a critical-severity vulnerability in Starkbank Elixir Ecdsa with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-347.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (59th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-347
Affected product: Starkbank Elixir Ecdsa
Published: 2021-11-09
Last modified: 2026-06-17

Description

The verify function in the Stark Bank Elixir ECDSA library (ecdsa-elixir) 1.0.0 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.

Frequently asked questions

What is CVE-2021-43568?: The verify function in the Stark Bank Elixir ECDSA library (ecdsa-elixir) 1.0.0 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.
How severe is CVE-2021-43568?: CVE-2021-43568 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-43568 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-43568?: CVE-2021-43568 affects Starkbank Elixir Ecdsa. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-43568?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-43568 published?: CVE-2021-43568 was published on 2021-11-09 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:starkbank:elixir_ecdsa:1.0.0:*:*:*:*:*:*:*

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