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Vulnerability record · public intelligence
CVE-2020-26137
UNKNOWN

CRLF injection in urllib3

Published Sep 29, 2020 · Updated Nov 3, 2026

Severity · CVSSUNKNOWN · Not scored
Known exploitationNot listed
EPSS / likelihood2.27%
QFinch risk scoreNot available

Original summary

Normalized public record · Updated Nov 3, 2026

CRLF injection in urllib3

Publisher and source text is retained separately from QFinch interpretation.

QFinch assessment

urllib3 before 1.25.9 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 `putrequest()`. NOTE: this is similar to CVE-2020-26116.

Evidence: public source records

Affected products

Affected scope reported by the available public evidence
Affected package, product or rangeFix status
Consult the referenced vendor advisory for affected versions.Consult source advisory

Matching a version is only one part of assessing exposure. QFinch has not assessed your environment on this public page.

Remediation

Apply the vendor-supported fixed release or mitigation, then verify the affected component is no longer reachable.

  1. Confirm the affected product and reachable code path exist in your environment.
  2. Apply the vendor-supported patch or mitigation from the primary advisory.
  3. Rescan the exact deployed revision and retain verification evidence.
Review primary references

Evidence coverage

FIRST-EPSSCVE-LIST-V5
SSVC priority
LOW
Confidence
Not available
Aliases
None reported

Scores appear only when corresponding evidence exists. Missing data is never interpreted as zero risk.

Sources and record history

  1. bugs.python.org ↗
  2. Source repository ↗
  3. Patch commit ↗
  4. USN-4570-1 ↗
  5. [debian-lts-announce] 20210615 [SECURITY] [DLA 2686-1] python-urllib3 security update ↗
  6. www.oracle.com ↗
  7. www.oracle.com ↗
  8. [debian-lts-announce] 20231008 [SECURITY] [DLA 3610-1] python-urllib3 security update ↗

Record history

Published Sep 29, 2020 · Last refreshed Nov 3, 2026

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