CVE-2016-5420
mediumpriority · track · 35EPSS 0.154 · 97 %ileDEEUUSEPSS · scored 2026-10-28
curl and libcurl before 7.50.1 do not check the client certificate when choosing the TLS connection to reuse, which might allow remote attackers to hijack the authentication of the connection by leveraging a previously created connection with a different client certificate.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5–7.5
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (6)
Products and version ranges known to be affected.
advisories (2)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-0180Dell Data Protection Advisor: Mehrere SchwachstellenDeutsch2026-01-20csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Dell Data Protection Advisor ausnutzen, um beliebigen Code auszuführen, einen Denial-of-Service-Zustand zu erzeugen, Sicherheitsmaßnahmen zu umgehen und nicht näher spezifizierte Angriffe zu starten.
- CURL-CVE-2016-5420Reusing connections with wrong client cert2016-08-03vendor · osvUS
libcurl did not consider client certificates when reusing TLS connections. libcurl supports reuse of established connections for subsequent requests. It does this by keeping a few previous connections "alive" in a connection pool so that a subsequent request that can use one of them instead of creating a new connection. When using a client certificate for a connection that was then put into the connection pool, that connection could then wrongly get reused in a subsequent request to that same server that either did not use a client certificate at all or that asked to use a different client certificate thus trying to tell the user that it is a different entity. This mistakenly using the wrong connection could of course lead to applications sending requests to the wrong realms of the server using authentication that it was not supposed to have for those operations.
also known as (3)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (38)
External citations — patches, advisories, analysis.
- http://www.debian.org/security/2016/dsa-3638cnnvd
- https://curl.haxx.se/docs/adv_20160803B.htmlcnnvd
- http://lists.opensuse.org/opensuse-updates/2016-09/msg00011.htmlenisa_euvd
- http://lists.opensuse.org/opensuse-updates/2016-09/msg00094.htmlenisa_euvd
- http://rhn.redhat.com/errata/RHSA-2016-2575.htmlenisa_euvd
- http://rhn.redhat.com/errata/RHSA-2016-2957.htmlenisa_euvd
- http://www.debian.org/security/2016/dsa-3638enisa_euvd
- http://www.oracle.com/technetwork/security-advisory/cpuoct2018-4428296.htmlenisa_euvd
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