Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2020-26263

23
FAUCET Score

CVE-2020-26263 is a high-severity side-channel vulnerability affecting tlslite-ng, an open-source Python library for SSL/TLS. The flaw lies in the RSA PKCS#1 v1.5 decryption process, where data-dependent timing differences can leak information about the decrypted ciphertext, impacting TLS servers using RSA key exchange or applications directly using the RSA decryption API. With a CVSS score of 7.5, this vulnerability allows for high confidentiality impact with low attack complexity and no user interaction required. While patches exist in versions 0.7.6 and 0.8.0-alpha39, their side-channel resistance is limited due to Python's byte processing. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.7.6CPE matchmatch criteria
cpe:2.3:a:tlslite-ng_project:tlslite-ng:*:*:*:*:*:*:*:*
0.8.0CPE matchmatch criteria
cpe:2.3:a:tlslite-ng_project:tlslite-ng:0.8.0:alpha1:*:*:*:*:*:*
0.8.0CPE matchmatch criteria
cpe:2.3:a:tlslite-ng_project:tlslite-ng:0.8.0:alpha10:*:*:*:*:*:*
0.8.0CPE matchmatch criteria
cpe:2.3:a:tlslite-ng_project:tlslite-ng:0.8.0:alpha11:*:*:*:*:*:*
0.8.0CPE matchmatch criteria
cpe:2.3:a:tlslite-ng_project:tlslite-ng:0.8.0:alpha12:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.50%
Probability of exploitation in next 30 days
EPSS Percentile
71.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0150 is in the 53rd percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
pippatch availablevia ghsa
Product: tlslite-ngFixed in: 0.7.6

Vendor Advisories (1)

pipGHSA-wvcv-832q-fjg7high

RSA weakness in tslite-ng

Dec 21, 2020

References

github.com / tlsfuzzer/tlslite-ng/commit/c28d6d387bba59d8bd5cb3ba15edc42edf54b368
PatchThird Party Advisory
github.com / tlsfuzzer/tlslite-ng/pull/438
PatchThird Party Advisory
github.com / tlsfuzzer/tlslite-ng/pull/439
PatchThird Party Advisory
github.com / tlsfuzzer/tlslite-ng/security/advisories/GHSA-wvcv-832q-fjg7
ExploitPatchThird Party Advisory
pypi.org / project/tlslite-ng
ProductThird Party Advisory
securitypitfalls.wordpress.com / 2018/08/03/constant-time-compare-in-python
ExploitThird Party Advisory