CVE-2018-1000159: tlslite-ng version 0.7.3 and earlier, since commit d7b288316bca7bcdd082e6ccff5491e241305233 contains a CWE-354

Q: How do I fix CVE-2018-1000159?

tlslite-ng: upgrade to newer than 0.7.3. Exact commands for each OS are on this page.

Q: Is CVE-2018-1000159 being exploited?

CVE-2018-1000159 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-2018-1000159 affect?

CVE-2018-1000159 affects tlslite-ng. Severity is medium (CVSS 5.9). tlslite-ng version 0.7.3 and earlier, since commit d7b288316bca7bcdd082e6ccff5491e241305233 contains a CWE-354: Improper Validation of Integrity Check Value vulnerability in TLS implementation, tlslite/utils/constanttime.py: ct_check_cbc_ma

Q: How urgent is CVE-2018-1000159?

Priority 40/100. Remotely exploitable, no login, no user action

This month

MEDIUM 5.9REMOTEUPGRADE

CVE-2018-1000159 is a medium-severity flaw (CVSS 5.9) affecting tlslite-ng. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

tlslite-ng version 0.7.3 and earlier, since commit d7b288316bca7bcdd082e6ccff5491e241305233 contains a CWE-354: Improper Validation of Integrity Check Value vulnerability in TLS implementation, tlslite/utils/constanttime.py: ct_check_cbc_mac_and_pad(); line "end_pos = data_len - 1 - mac.digest_size" that can result in an attacker manipulating the TLS ciphertext which will not be detected by receiving tlslite-ng. This attack appears to be exploita

Why this priority

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	0.8% (top 44%)
CISA exploited list	No
Weakness	CWE-354
Published	2018-04-18
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: tlslite-ng project

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

Am I affected?

Timeline

2018-04-18 19:29 UTCPublished CVE record published
2026-06-17 01:32 UTCUpdated Record last modified

tlslite-ng project tlslite-ng UPGRADE

Affected: <= 0.7.3

Fixed in: newer than 0.7.3

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy tlslite-ng || rpm -q tlslite-ng || tlslite-ng --version

2. UPGRADE to newer than 0.7.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade tlslite-ng

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade tlslite-ng

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-2018-1000159?

tlslite-ng: upgrade to newer than 0.7.3. Exact commands for each OS are on this page.

Is CVE-2018-1000159 being exploited?

CVE-2018-1000159 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-2018-1000159 affect?

CVE-2018-1000159 affects tlslite-ng. Severity is medium (CVSS 5.9). tlslite-ng version 0.7.3 and earlier, since commit d7b288316bca7bcdd082e6ccff5491e241305233 contains a CWE-354: Improper Validation of Integrity Check Value vulnerability in TLS implementation, tlslite/utils/constanttime.py: ct_check_cbc_ma

How urgent is CVE-2018-1000159?

Priority 40/100. Remotely exploitable, no login, no user action

Related CVEs

CVE-2020-26263 HIGH 7.5 UPGRADE tlslite-ng is an open source python library that implements SSL and TLS cryptographic protocols

References

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