PatchTheCVECVE-2020-26263: tlslite-ng is an open source python library that implements SSL and TLS cryptographic protocols
CVE-2020-26263 is a high-severity flaw (CVSS 7.5) affecting tlslite-ng. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
tlslite-ng is an open source python library that implements SSL and TLS cryptographic protocols. In tlslite-ng before versions 0.7.6 and 0.8.0-alpha39, the code that performs decryption and padding check in RSA PKCS#1 v1.5 decryption is data dependant. In particular, the code has multiple ways in which it leaks information about the decrypted ciphertext. It aborts as soon as the plaintext doesn't start with 0x00, 0x02. All TLS servers that enable
Why this priority
- High severity
- Public exploit reference
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 7.5 (High) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 1.5% (top 25%) |
| CISA exploited list | No |
| Weakness | CWE-326 |
| Published | 2020-12-21 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
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-2020-26263?
tlslite-ng: upgrade to 0.7.6. Exact commands for each OS are on this page.
Is CVE-2020-26263 being exploited?
CVE-2020-26263 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-2020-26263 affect?
CVE-2020-26263 affects tlslite-ng. Severity is high (CVSS 7.5). tlslite-ng is an open source python library that implements SSL and TLS cryptographic protocols. In tlslite-ng before versions 0.7.6 and 0.8.0-alpha39, the code that performs decryption and padding check in RSA PKCS#1 v1.5 decryption is dat
How urgent is CVE-2020-26263?
Priority 55/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action
Software pages
Related CVEs
- CVE-2018-1000159 MEDIUM 5.9 UPGRADE tlslite-ng version 0.7.3 and earlier, since commit d7b288316bca7bcdd082e6ccff5491e241305233 contains a CWE-354