Bug 1887319 (CVE-2020-25648) - CVE-2020-25648 nss: TLS 1.3 CCS flood remote DoS Attack
Summary: CVE-2020-25648 nss: TLS 1.3 CCS flood remote DoS Attack
Status: NEW
Alias: CVE-2020-25648
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 1887720 1887721 1889579
Blocks: 1887320
TreeView+ depends on / blocked
Reported: 2020-10-12 06:14 UTC by Huzaifa S. Sidhpurwala
Modified: 2020-10-20 04:43 UTC (History)
7 users (show)

Fixed In Version: nss 3.58
Doc Type: If docs needed, set a value
Doc Text:
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.
Clone Of:
Last Closed:

Attachments (Terms of Use)

Description Huzaifa S. Sidhpurwala 2020-10-12 06:14:32 UTC
NSS allows an attacker to send CCS messages in a row after ClientHello message. If an attacker put multiple CCS messages in a single tcp packet, the NSS server will stuck in a loop for many times to process the messages. 

This issue affects servers which are compiled against the NSS library. Other consumers of NSS like firefox etc are not affected by this flaw.

Comment 2 Huzaifa S. Sidhpurwala 2020-10-13 08:04:31 UTC
Upstream patch: https://hg.mozilla.org/projects/nss/rev/57bbefa793232586d27cee83e74411171e128361
Upstream bug (currently private): https://bugzilla.mozilla.org/show_bug.cgi?id=1641480

Comment 4 RaTasha Tillery-Smith 2020-10-15 19:23:58 UTC

This flaw only affects servers that are compiled with the NSS library and when the TLS 1.3 protocol is used.

Comment 5 Huzaifa S. Sidhpurwala 2020-10-20 04:00:25 UTC
External References:


Comment 6 Huzaifa S. Sidhpurwala 2020-10-20 04:02:07 UTC

Name: the Mozilla project

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