CVE-2018-12404: A cached side channel attack during handshakes using RSA encryption could allow for the decryption of encrypte

Q: How do I fix CVE-2018-12404?

network security services: upgrade to 3.41. Exact commands for each OS are on this page.

Q: Is CVE-2018-12404 being exploited?

CVE-2018-12404 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-2018-12404 affect?

CVE-2018-12404 affects network security services. Severity is medium (CVSS 5.9). A cached side channel attack during handshakes using RSA encryption could allow for the decryption of encrypted content. This is a variant of the Adaptive Chosen Ciphertext attack (AKA Bleichenbacher attack) and affects all NSS versions pri

Q: How urgent is CVE-2018-12404?

Priority 50/100. EPSS top 1%: very likely to be exploited; Remotely exploitable, no login, no user action

This week

MEDIUM 5.9REMOTEUPGRADE

CVE-2018-12404 is a medium-severity flaw (CVSS 5.9) affecting network security services. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A cached side channel attack during handshakes using RSA encryption could allow for the decryption of encrypted content. This is a variant of the Adaptive Chosen Ciphertext attack (AKA Bleichenbacher attack) and affects all NSS versions prior to NSS 3.41.

Why this priority

EPSS top 1%: very likely to be exploited
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	44.2% (top 1%)
CISA exploited list	No
Published	2019-05-02
Last modified	2026-06-17

Publisher (CNA): Mozilla Corporation · Vendor: mozilla

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

Am I affected?

Timeline

2019-05-02 17:29 UTCPublished CVE record published
2026-06-17 01:37 UTCUpdated Record last modified

mozilla network security services UPGRADE

Affected: < 3.41

Fixed in: 3.41

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy network-security-services || rpm -q network-security-services || network-security-services --version

2. UPGRADE to 3.41 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade network-security-services

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade network-security-services

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-2018-12404?

network security services: upgrade to 3.41. Exact commands for each OS are on this page.

Is CVE-2018-12404 being exploited?

CVE-2018-12404 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-2018-12404 affect?

CVE-2018-12404 affects network security services. Severity is medium (CVSS 5.9). A cached side channel attack during handshakes using RSA encryption could allow for the decryption of encrypted content. This is a variant of the Adaptive Chosen Ciphertext attack (AKA Bleichenbacher attack) and affects all NSS versions pri

How urgent is CVE-2018-12404?

Priority 50/100. EPSS top 1%: very likely to be exploited; Remotely exploitable, no login, no user action

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References

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