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.
CVE-2020-26137
This medium-severity CVE scores 6.5 under NVD CVSS v3. EPSS exploit probability: 2.3%, top 19% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
A fix is available — apply it.
- CVSS v3
- 6.5
- EG Score
- 6.5(medium)
- EG Risk
- 35(Track)EG Risk 35/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity65% × 45%Exploitation2% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS
- 81.2%
- KEV
- Not listed
Published
September 30, 2020
Last Modified
November 21, 2024
References (16)
- cve@mitrehttps://bugs.python.org/issue39603
- cve@mitrehttps://github.com/urllib3/urllib3/commit/1dd69c5c5982fae7c87a620d487c2ebf7a6b436b
- cve@mitrehttps://github.com/urllib3/urllib3/pull/1800
- cve@mitrehttps://lists.debian.org/debian-lts-announce/2021/06/msg00015.html
- cve@mitrehttps://lists.debian.org/debian-lts-announce/2023/10/msg00012.html
- cve@mitrehttps://usn.ubuntu.com/4570-1/
- cve@mitrehttps://www.oracle.com/security-alerts/cpujul2022.html
- cve@mitrehttps://www.oracle.com/security-alerts/cpuoct2021.html
- af854a3a-2127-422b-91ae-364da2661108https://bugs.python.org/issue39603
- af854a3a-2127-422b-91ae-364da2661108https://github.com/urllib3/urllib3/commit/1dd69c5c5982fae7c87a620d487c2ebf7a6b436b
- af854a3a-2127-422b-91ae-364da2661108https://github.com/urllib3/urllib3/pull/1800
- af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2021/06/msg00015.html
- af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2023/10/msg00012.html
- af854a3a-2127-422b-91ae-364da2661108https://usn.ubuntu.com/4570-1/
- af854a3a-2127-422b-91ae-364da2661108https://www.oracle.com/security-alerts/cpujul2022.html
Vendor Advisories for CVE-2020-26137(3)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2022:5235Red Hat Product SecurityMedium
Red Hat Security Advisory: python security update
- RHSA-2021:0079Red Hat Product SecurityMedium
Red Hat Security Advisory: OpenShift Container Platform 3.11.374 bug fix and security update
- RHSA-2020:4299Red Hat Product SecurityMedium
Red Hat Security Advisory: rh-python38 security, bug fix, and enhancement update
Patch Availability(6)
| Vendor / Ecosystem | Fixed in / Patch | Released | Source |
|---|---|---|---|
| ubuntu | python3-urllib3 (1.22-1ubuntu0.18.04.2) @ bionic | 2026-05-23 | ubuntu |
| redhat | python-0:2.7.5-92.el7_9 | 2022-06-28 | redhat |
| redhat | python27:2.7-8040020210122160212.cdb2db54 | 2021-05-18 | redhat |
| redhat | python-urllib3-0:1.24.2-5.el8 | 2021-05-18 | redhat |
| redhat | python-urllib3-0:1.26.2-1.el7 | 2021-01-20 | redhat |
| redhat | rh-python38-python-urllib3-0:1.25.7-6.el7 | 2020-10-20 | redhat |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(1 across 1 ecosystem)
PyPI(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| urllib3 | 0.2 ... 1.25.8 (59 versions) | 1.25.9 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Additional Vendor Advisories
(5)
Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.
- Microsoft MSRCCVE-2020-261372020-12-21
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.
- Red HatRHSA-2021:0034MODERATE2020-02-10
RHSA-2021:0034 — Moderate
- Red HatRHSA-2021:1631MODERATE2020-02-10
RHSA-2021:1631 — Moderate
- Red HatRHSA-2021:1761MODERATE2020-02-10
RHSA-2021:1761 — Moderate
- UbuntuUSN-4570-1MEDIUM
urllib3 vulnerability
Data Freshness Timeline
(refreshed 12× in last 7d / 45× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-23 01:51 UTCEG score recompute
- 2026-07-22 22:37 UTCEG score recompute
- 2026-07-22 14:05 UTCEPSS rescore
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- 2026-05-23 07:09 UTCEG score recompute
- 2026-05-23 07:09 UTCVendor advisory
Related CVEs(same vendor + same CWE)
Same vendor
10 shownmsrc · redhat
Same CWE
10 shownCWE-74
- CVE-2015-10062NVD 5.5EG 9.8MEDIUM
- CVE-2015-10027NVD 5.5EG 9.8MEDIUM
- CVE-2016-15007NVD 5.5EG 9.8MEDIUM
- CVE-2016-15004NVD 7.3EG 9.8HIGH
- CVE-2013-4144EG 9.8CRITICAL
- CVE-2013-7487EG 9.8CRITICAL
- CVE-2014-4678EG 9.8EPSS 92%CRITICAL
- CVE-2014-4967EG 9.8CRITICAL
- CVE-2014-4966EG 9.8CRITICAL
- CVE-2013-7381EG 9.8CRITICAL
Frequently asked(5)
What is CVE-2020-26137?
When was CVE-2020-26137 disclosed?
Is CVE-2020-26137 actively exploited?
What is the CVSS score of CVE-2020-26137?
How do I remediate CVE-2020-26137?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2020-26137
Is Your Infrastructure Affected by CVE-2020-26137?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.