CVE-2018-12437: LibTomCrypt through 1.18.1 allows a memory-cache side-channel attack on ECDSA signatures, aka the Return Of th

Q: How do I fix CVE-2018-12437?

libtomcrypt: upgrade to newer than 1.18.1; op-tee: upgrade to newer than 3.5.0. Exact commands for each OS are on this page.

Q: Is CVE-2018-12437 being exploited?

CVE-2018-12437 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-2018-12437 affect?

CVE-2018-12437 affects libtomcrypt, op-tee. Severity is medium (CVSS 4.9). LibTomCrypt through 1.18.1 allows a memory-cache side-channel attack on ECDSA signatures, aka the Return Of the Hidden Number Problem or ROHNP. To discover an ECDSA key, the attacker needs access to either the local machine or a different v

Q: How urgent is CVE-2018-12437?

Priority 33/100. Public exploit reference

Routine

MEDIUM 4.9UPGRADEUPGRADE

CVE-2018-12437 is a medium-severity flaw (CVSS 4.9) affecting libtomcrypt, op-tee. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

LibTomCrypt through 1.18.1 allows a memory-cache side-channel attack on ECDSA signatures, aka the Return Of the Hidden Number Problem or ROHNP. To discover an ECDSA key, the attacker needs access to either the local machine or a different virtual machine on the same physical host.

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	0.5% (top 55%)
CISA exploited list	No
Weakness	CWE-200
Published	2018-06-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: libtom · trustedfirmware

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

libtom libtomcrypt UPGRADE

Affected: <= 1.18.1

Fixed in: newer than 1.18.1

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 1.18.1 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libtomcrypt

Note

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

trustedfirmware op-tee UPGRADE

Affected: <= 3.5.0

Fixed in: newer than 3.5.0

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2018-12437?

libtomcrypt: upgrade to newer than 1.18.1; op-tee: upgrade to newer than 3.5.0. Exact commands for each OS are on this page.

Is CVE-2018-12437 being exploited?

CVE-2018-12437 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-2018-12437 affect?

CVE-2018-12437 affects libtomcrypt, op-tee. Severity is medium (CVSS 4.9). LibTomCrypt through 1.18.1 allows a memory-cache side-channel attack on ECDSA signatures, aka the Return Of the Hidden Number Problem or ROHNP. To discover an ECDSA key, the attacker needs access to either the local machine or a different v

How urgent is CVE-2018-12437?

Priority 33/100. Public exploit reference

Related CVEs

CVE-2019-17362 CRITICAL 9.1 UPGRADE MITIGATE In LibTomCrypt through 1.18.2, the der_decode_utf8_string function (in der_decode_utf8_string.c) does not prop
CVE-2016-6129 HIGH 7.5 UPGRADE UPGRADE The rsa_verify_hash_ex function in rsa_verify_hash.c in LibTomCrypt, as used in OP-TEE before 2.2.0, does not
CVE-2005-1600 HIGH 7.5 DOWNGRADE A "mathematical flaw" in the implementation of the El Gamal signature algorithm for LibTomCrypt 1.0 to 1.0.2 a

References

← Back to latest CVEs