CVE-2018-12433: cryptlib through 3.4.4 allows a memory-cache side-channel attack on DSA and ECDSA signatures, aka the Return O

Q: How do I fix CVE-2018-12433?

cryptlib: upgrade to newer than 3.4.4. Exact commands for each OS are on this page.

Q: Is CVE-2018-12433 being exploited?

CVE-2018-12433 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2018-12433 affect?

CVE-2018-12433 affects cryptlib. Severity is medium (CVSS 4.9). cryptlib through 3.4.4 allows a memory-cache side-channel attack on DSA and ECDSA signatures, aka the Return Of the Hidden Number Problem or ROHNP. To discover a key, the attacker needs access to either the local machine or a different virt

Q: How urgent is CVE-2018-12433?

Priority 29/100. Public exploit reference

Routine

MEDIUM 4.9UPGRADE

CVE-2018-12433 is a medium-severity flaw (CVSS 4.9) affecting cryptlib. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

cryptlib through 3.4.4 allows a memory-cache side-channel attack on DSA and ECDSA signatures, aka the Return Of the Hidden Number Problem or ROHNP. To discover a key, the attacker needs access to either the local machine or a different virtual machine on the same physical host. NOTE: the vendor does not include side-channel attacks within its threat model

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	4.9 (Medium)
Attack vector	Physical
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 72%)
CISA exploited list	No
Weakness	CWE-200, CWE-320
Published	2018-06-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: cryptlib

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2018-06-15 02:29 UTCPublished CVE record published
2026-06-17 01:37 UTCUpdated Record last modified

cryptlib cryptlib UPGRADE

Affected: <= 3.4.4

Fixed in: newer than 3.4.4

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy cryptlib || rpm -q cryptlib || cryptlib --version

2. UPGRADE to newer than 3.4.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade cryptlib

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade cryptlib

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2018-12433?

cryptlib: upgrade to newer than 3.4.4. Exact commands for each OS are on this page.

Is CVE-2018-12433 being exploited?

CVE-2018-12433 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2018-12433 affect?

CVE-2018-12433 affects cryptlib. Severity is medium (CVSS 4.9). cryptlib through 3.4.4 allows a memory-cache side-channel attack on DSA and ECDSA signatures, aka the Return Of the Hidden Number Problem or ROHNP. To discover a key, the attacker needs access to either the local machine or a different virt

How urgent is CVE-2018-12433?

Priority 29/100. Public exploit reference

References

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