HOMEVULNERABILITIESCVE-2020-26116
HIGH

CVE-2020-26116

CWE-74Published: September 27, 2020· Updated: Jun 17, 2026

7.2
CVSS v3.1

Official Description

http.client in Python 3.x before 3.5.10, 3.6.x before 3.6.12, 3.7.x before 3.7.9, and 3.8.x before 3.8.5 allows CRLF injection if the attacker controls the HTTP request method, as demonstrated by inserting CR and LF control characters in the first argument of HTTPConnection.request.

NVD Source

Technical Analysis

CVE-2020-26116 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeChanged
Impact
ConfidentialityLow
IntegrityLow
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

Affected Vendors & Products

Canonical1 product(s)
ubuntu linux
Debian1 product(s)
debian linux
Fedora1 product(s)
fedora
netapp3 product(s)
solidfirehci compute nodehci storage node
openSUSE1 product(s)
leap
Oracle1 product(s)
zfs storage appliance kit
Python1 product(s)
python
Source: NVD CPE · 14 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://bugs.python.org/issue39603
PATCHhttps://python-security.readthedocs.io/vuln/http-header-injection-method.html
PATCHhttps://www.oracle.com/security-alerts/cpuoct2021.html
PATCHhttps://bugs.python.org/issue39603
PATCHhttps://python-security.readthedocs.io/vuln/http-header-injection-method.html
PATCHhttps://www.oracle.com/security-alerts/cpuoct2021.html
ADVISORYhttp://lists.opensuse.org/opensuse-security-announce/2020-11/msg00027.html
ADVISORYhttps://lists.debian.org/debian-lts-announce/2020/11/msg00032.html
ADVISORYhttps://security.gentoo.org/glsa/202101-18
ADVISORYhttps://security.netapp.com/advisory/ntap-20201023-0001/
ADVISORYhttps://usn.ubuntu.com/4581-1/
ADVISORYhttp://lists.opensuse.org/opensuse-security-announce/2020-11/msg00027.html
ADVISORYhttps://lists.debian.org/debian-lts-announce/2020/11/msg00032.html
ADVISORYhttps://security.gentoo.org/glsa/202101-18
ADVISORYhttps://security.netapp.com/advisory/ntap-20201023-0001/
ADVISORYhttps://usn.ubuntu.com/4581-1/

All References (28)

→
http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00027.htmlMailing List · Third Party Advisory
→
https://bugs.python.org/issue39603Exploit · Issue Tracking · Patch · Vendor Advisory
→
https://lists.debian.org/debian-lts-announce/2020/11/msg00032.htmlMailing List · Third Party Advisory
→
https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BW4GCLQISJCOEGQNIMVUZDQMIY6RR6CC/
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HDQ2THWU4GPV4Y5H5WW5PFMSWXL2CRFD/
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JWMAVY4T4257AZHTF2RZJKNJNSJFY24O/
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OXI72HIHMXCQFWTULUXDG7VDA2BCYL4Y/
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QOX7DGMMWWL6POCRYGAUCISOLR2IG3XV/
→
https://python-security.readthedocs.io/vuln/http-header-injection-method.htmlPatch · Third Party Advisory
→
https://security.gentoo.org/glsa/202101-18Third Party Advisory
→
https://security.netapp.com/advisory/ntap-20201023-0001/Third Party Advisory
→
https://usn.ubuntu.com/4581-1/Third Party Advisory
→
https://www.oracle.com/security-alerts/cpuoct2021.htmlPatch · Third Party Advisory
→
http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00027.htmlMailing List · Third Party Advisory

Quick Facts

CVE IDCVE-2020-26116
CVSS Score7.2 / 10
SeverityHIGH
WeaknessCWE-74
CISA KEVNo
Affected7 vendor(s)
PublishedSep 27, 2020

Related CVEs (CWE-74)

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CVE-2024-38366
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CVE-2020-26282
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CVE-2026-56699
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CVE-2023-1523
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CVE-2026-44182
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Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2020-26116 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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