CVE-2016-5420: debian debian_linux Improper Authorization
Vulnerability summary
CVE-2016-5420 is a high (CVSS 7.5) Improper Authorization vulnerability in debian debian_linux. EPSS estimates a 15.36% chance of exploitation in the next 30 days, higher than 96.7% of scored vulnerabilities.
Severe, CVSS 7.5 (NVD); no exploitation reported by the 5 checked sources; EPSS 15% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 10 · Related 5Timeline
- 10-08-2016PublishedVulnerability first disclosed.
- 06-08-2024Last modifiedVulnerability information updated.
Description
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 metrics
5 scores · 4 sources · 2 versions- OSV · AlpineEcosystem advisory · calculated7.5HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS trend
Probability
15.36%
Chance of exploitation in the next 30 days
Percentile
97%
Versus all other CVEs
30-day change
No change 0.00 pp
From 15.36% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Debian2 products
- curl< 7.50.1-1
- debian_linuxEOL8.0
Alpine1 product
- curl< 7.50.1-r0 | < 7.50.1 | < 7.49.1-r1
Haxx1 product
- libcurl≤ 7.50.0
Opensuse1 product
- leapEOL42.1
Ubuntu1 product
- curl< 7.35.0-1ubuntu2.8 | < 7.47.0-1ubuntu2.1
5 vendors · 6 products
References
24 links- source.android.com/security/bulletin/2016-12-01.htmlX Refsource CONFIRM
- www.slackware.com/security/viewer.php?l=slackware-security&y=2016&m=slackware-security.563059Vendor AdvisoryX Refsource SLACKWARE
- www.tenable.com/security/tns-2016-18X Refsource CONFIRM
- lists.opensuse.org/opensuse-updates/2016-09/msg00094.htmlVendor AdvisoryX Refsource SUSEThird Party Advisory
Show all 24 references
- www.oracle.com/technetwork/security-advisory/cpuoct2018-4428296.htmlX Refsource CONFIRM