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Fencer Vulns
high 7.5

CVE-2020-35680 json

smtpd/lka_filter.c in OpenSMTPD before 6.8.0p1, in certain configurations, allows remote attackers to cause a denial of service (NULL point…

published 2020-12-24 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-23340

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.7%
EPSS 3.7% chance of exploitation in 30 days, percentile 89%
public exploits
0
none known

Summary

smtpd/lka_filter.c in OpenSMTPD before 6.8.0p1, in certain configurations, allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via a crafted pattern of client activity, because the filter state machine does not properly maintain the I/O channel between the SMTP engine and the filters layer.

Patch / fix

  • opensmtpd opensmtpd 6.8.0
  • opensmtpd Debian 14, Debian 13, Debian 12 6.8.0p2-1

debian advisories DEBIAN-CVE-2020-35680

  • opensmtpd Alpine 3.11 6.6.4p1-r1
  • opensmtpd Alpine 3.12 6.6.4p1-r2
  • opensmtpd Alpine 3.13 6.7.1p1-r1

alpine advisories ALPINE-CVE-2020-35680

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • opensmtpd Arch Linux 6.8.0p2-1

arch linux advisories AVG-1381

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-35680 updated cvss 7.5

opensmtpd: NULL pointer dereference via a crafted pattern of client activity

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

3.65% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness

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.