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Fencer Vulns
high 7.5

CVE-2020-25648 json

A flaw was found in the way NSS handled CCS (ChangeCipherSpec) messages in TLS 1.3.

published 2020-10-20 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-18313

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.5%
EPSS 3.5% chance of exploitation in 30 days, percentile 89%
public exploits
0
none known

Summary

A flaw was found in the way NSS handled CCS (ChangeCipherSpec) messages in TLS 1.3. This flaw allows a remote attacker to send multiple CCS messages, causing a denial of service for servers compiled with the NSS library. The highest threat from this vulnerability is to system availability. This flaw affects NSS versions before 3.58.

Patch / fix

  • mozilla network_security_services 3.58
  • oracle jd_edwards_enterpriseone_tools 9.2.6.0
  • nss Debian 14, Debian 13, Debian 12 2:3.58-1

debian advisories DEBIAN-CVE-2020-25648

  • nss Ubuntu 18.04 LTS 2:3.35-2ubuntu2.14
  • nss Ubuntu 20.04 LTS 2:3.49.1-1ubuntu1.7

ubuntu advisories UBUNTU-CVE-2020-25648

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • nss RHEL 8 3.67.0-6.el8_4
  • nspr RHEL 8 4.32.0-1.el8_4
  • nss-util RHEL 8 3.67.0-6.el8_4
  • nss-tools RHEL 8 3.67.0-6.el8_4
  • nss-softokn RHEL 8 3.67.0-6.el8_4
  • nss-sysinit RHEL 8 3.67.0-6.el8_4
  • nss-softokn-freebl RHEL 8 3.67.0-6.el8_4
  • nss RHEL 7 3.53.1-7.el7_9

red hat advisories RHSA-2021:3572RHSA-2021:1384

  • mozilla-nss SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 3.68-47.16.1
  • mozilla-nspr SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 4.32-33.6.1
  • mozilla-nss SLES 15 SP1-BCL, SLE Module for Server Applications 15 SP3, SLE Module for Server Applications 15 SP2 +16 more 3.68-3.56.1
  • mozilla-nspr SLES 15 SP1-BCL, SLE Module for Basesystem 15 SP3, SLE Module for Basesystem 15 SP2 +14 more 4.32-3.20.1
  • mozilla-nss SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +11 more 3.68-58.54.1
  • mozilla-nspr SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +11 more 4.32-19.18.1

suse advisories SUSE-RU-2021:14818-1SUSE-RU-2021:3115-2SUSE-RU-2021:3116-1SUSE-RU-2021:3115-1

  • mozilla-nss openSUSE Tumbleweed 3.69.1-1.2

opensuse advisories openSUSE-SU-2024:11058-1

  • nss AlmaLinux 8 3.67.0-6.el8_4
  • nspr AlmaLinux 8 4.32.0-1.el8_4
  • nss-util AlmaLinux 8 3.67.0-6.el8_4
  • nss-tools AlmaLinux 8 3.67.0-6.el8_4
  • nss-softokn AlmaLinux 8 3.67.0-6.el8_4
  • nss-sysinit AlmaLinux 8 3.67.0-6.el8_4
  • nss-softokn-freebl AlmaLinux 8 3.67.0-6.el8_4

almalinux advisories ALSA-2021:3572

  • nss Rocky Linux 8 3.67.0-6.el8_4
  • nspr Rocky Linux 8 4.32.0-1.el8_4

rocky linux advisories RLSA-2021:3572

  • nss Alpine 3.24, Alpine 3.23, Alpine 3.22 +10 more 3.58-r0

alpine advisories ALPINE-CVE-2020-25648

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

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-2020-25648 updated cvss 7.5

nss: TLS 1.3 CCS flood remote DoS Attack

  • Red Hat Enterprise Linux 5 nss Red Hat Enterprise Linux 6 nss, nss-tools, nss-sysinit
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) nss 3.67.0-6.el8_4, nspr 4.32.0-1.el8_4, nss-util 3.67.0-6.el8_4, nss-tools 3.67.0-6.el8_4, nss-softokn 3.67.0-6.el8_4, nss-sysinit 3.67.0-6.el8_4, +1 more
    fixed: vendor fix RHSA-2021:3572
  • Red Hat Enterprise Linux Client (v. 7) nss 3.53.1-7.el7_9, nss-tools 3.53.1-7.el7_9, nss-sysinit 3.53.1-7.el7_9 Red Hat Enterprise Linux Client Optional (v. 7) nss-devel 3.53.1-7.el7_9, nss-debuginfo 3.53.1-7.el7_9, nss-pkcs11-devel 3.53.1-7.el7_9 Red Hat Enterprise Linux ComputeNode Optional (v. 7) nss-devel 3.53.1-7.el7_9, nss-debuginfo 3.53.1-7.el7_9, nss-pkcs11-devel 3.53.1-7.el7_9 Red Hat Enterprise Linux Server (v. 7) nss 3.53.1-7.el7_9, nss-tools 3.53.1-7.el7_9, nss-sysinit 3.53.1-7.el7_9 Red Hat Enterprise Linux Server Optional (v. 7) nss-debuginfo 3.53.1-7.el7_9, nss-pkcs11-devel 3.53.1-7.el7_9 Red Hat Enterprise Linux Workstation (v. 7) nss 3.53.1-7.el7_9, nss-tools 3.53.1-7.el7_9, nss-sysinit 3.53.1-7.el7_9
    +1 more products
    Red Hat Enterprise Linux Workstation Optional (v. 7) nss-debuginfo 3.53.1-7.el7_9, nss-pkcs11-devel 3.53.1-7.el7_9
    fixed: vendor fix RHSA-2021:1384
  • Red Hat Migration Toolkit 1.4 rhmtc/openshift-migration-ui-rhel8 v1.4.6-4, rhmtc/openshift-velero-plugin-rhel8 v1.4.6-4, rhmtc/openshift-migration-velero-rhel8 v1.4.6-5, rhmtc/openshift-migration-registry-rhel8 v1.4.6-4, rhmtc/openshift-migration-operator-bundle v1.4.6-5, rhmtc/openshift-migration-controller-rhel8 v1.4.6-4, +7 more
    fixed: vendor fix RHBA-2021:2854

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

3.50% 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

Affected products

  • n/a nss

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

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.