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Fencer Vulns
high 7.4

CVE-2020-13163 json

Improper certificate validation in em-imap

published 2020-05-19 6 y ago modified 2026-06-17 4 mo ago also GHSA-4f68-49qq-h392 , EUVD-2021-0936

cvss
7.4
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 55%
public exploits
0
none known

Summary

em-imap 0.5 uses the library eventmachine in an insecure way that allows an attacker to perform a man-in-the-middle attack against users of the library. The hostname in a TLS server certificate is not verified.

Exploit prediction

0.77% chance of exploitation in the next 30 days, higher than 55% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/ConradIrwin/em-imap/issues/25 referenced PoC, tagged "exploit" by a source, unverified
  • securitylab.github.com https://securitylab.github.com/advisories/GHSL-2020-095-conradirwin-em-imap referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
NVD 2.0 5.8 AV:N/AC:M/Au:N/C:P/I:P/A:N
GitHub 3.1 7.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
rubygems em-imap
<=0.5
 no fix listed

Classification

Weakness
  • CWE-295 Improper Certificate Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.