Reference page — cumulative record through Monday, October 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2020-26116

CVE-2020-26116HIGH

n/a n/a — 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 att…

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   N  C  L  L  N    7.2   .0642   93.6     —

AFFECTED
  Product  Versions  Fixed
  n/a      n/a –     —

TIMELINE
  Sep 27  Reserved by mitre
  Sep 27  Published (CNA: mitre)
  Oct 8   ENRICHED — CVE-2020-26116. Received CVSS 7.2 and CPE data from NVD.
  Oct 8   EXPLOIT PUBLISHED — CVE-2020-26116. Public exploit reference added.
  Oct 14  EXPLOIT PUBLISHED — CVE-2020-26116. Public exploit reference added.

CWE-74 · CNA: mitre · CVSS v3.1 · 15 references · NVD status: Modified

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.

Lifecycle

Complete event history — 5 events, chronological
Date	Event	Detail
September 27, 2020	Reserved	Reserved by mitre
September 27, 2020	Published	Published (CNA: mitre)
October 8, 2026	ENRICHED	ENRICHED — CVE-2020-26116. Received CVSS 7.2 and CPE data from NVD.
October 8, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2020-26116. Public exploit reference added.
October 14, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2020-26116. Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
n/a	n/a	—	n/a	—

Weaknesses

CWE-74

References (15)

http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00027.html [Mailing List, Third Party Advisory]
https://bugs.python.org/issue39603 [Exploit, Issue Tracking, Patch, Vendor Advisory]
https://cert-portal.siemens.com/productcert/html/ssa-398330.html
https://lists.debian.org/debian-lts-announce/2020/11/msg00032.html [Mailing 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.html [Patch, Third Party Advisory]
https://security.gentoo.org/glsa/202101-18 [Third 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.html [Patch, Third Party Advisory]

Authoritative record: CVE-2020-26116 at cve.org

Weaknesses: CWE-74

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2020-26116 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Monday, October 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.