CVE-2019-1551

CVE-2019-1551 is a medium-severity vulnerability in Openssl with a CVSS 3.x base score of 5.3. Its EPSS exploit-prediction score of 14% places it in the 96th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-190.

Key facts

Description

There is an overflow bug in the x64_64 Montgomery squaring procedure used in exponentiation with 512-bit moduli. No EC algorithms are affected. Analysis suggests that attacks against 2-prime RSA1024, 3-prime RSA1536, and DSA1024 as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH512 are considered just feasible. However, for an attack the target would have to re-use the DH512 private key, which is not recommended anyway. Also applications directly using the low level API BN_mod_exp may be affected if they use BN_FLG_CONSTTIME. Fixed in OpenSSL 1.1.1e (Affected 1.1.1-1.1.1d). Fixed in OpenSSL 1.0.2u (Affected 1.0.2-1.0.2t).

Frequently asked questions

What is CVE-2019-1551?
There is an overflow bug in the x64_64 Montgomery squaring procedure used in exponentiation with 512-bit moduli. No EC algorithms are affected. Analysis suggests that attacks against 2-prime RSA1024, 3-prime RSA1536, and DSA1024 as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH512 are considered just feasible. However, for an attack the target would have to re-use the DH512 private key, which is not recommended anyway. Also applications directly using the low level API BN_mod_exp may be affected if they use BN_FLG_CONSTTIME. Fixed in OpenSSL 1.1.1e (Affected 1.1.1-1.1.1d). Fixed in OpenSSL 1.0.2u (Affected 1.0.2-1.0.2t).
How severe is CVE-2019-1551?
CVE-2019-1551 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2019-1551 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 14% (96th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-1551?
CVE-2019-1551 primarily affects Openssl. In total, 16 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-1551?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2019-1551 published?
CVE-2019-1551 was published on 2019-12-06 and last updated on 2026-06-17.

References

Affected products (16)

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Threat intelligence

Threat-intel indicators referencing this CVE: