How severe is CVE-2018-12440?

CVE-2018-12440 has a CVSS 3.x base score of 4.7, rated medium severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2018-12440 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-12440?

CVE-2018-12440 affects Google Boringssl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2018-12440?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2018-12440 published?

CVE-2018-12440 was published on 2018-06-15 and last updated on 2026-06-17.

CVE-2018-12440

CVE-2018-12440 is a medium-severity vulnerability in Google Boringssl with a CVSS 3.x base score of 4.7. 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-200.

Key facts

Severity: Medium (CVSS 3.x base score 4.7)
CVSS v2: 1.9
EPSS exploit prediction: 0% (4th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-200
Affected product: Google Boringssl
Published: 2018-06-15
Last modified: 2026-06-17

Description

BoringSSL through 2018-06-14 allows a memory-cache side-channel attack on DSA signatures, aka the Return Of the Hidden Number Problem or ROHNP. To discover a DSA key, the attacker needs access to either the local machine or a different virtual machine on the same physical host.

Frequently asked questions

What is CVE-2018-12440?: BoringSSL through 2018-06-14 allows a memory-cache side-channel attack on DSA signatures, aka the Return Of the Hidden Number Problem or ROHNP. To discover a DSA key, the attacker needs access to either the local machine or a different virtual machine on the same physical host.
How severe is CVE-2018-12440?: CVE-2018-12440 has a CVSS 3.x base score of 4.7, rated medium severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2018-12440 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-12440?: CVE-2018-12440 affects Google Boringssl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2018-12440?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2018-12440 published?: CVE-2018-12440 was published on 2018-06-15 and last updated on 2026-06-17.

References

https://www.nccgroup.trust/us/our-research/technical-advisory-return-of-the-hidden-number-problem/

Affected products (1)

cpe:2.3:a:google:boringssl:*:*:*:*:*:*:*:*

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