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 PROB
- 2%
- EPSS %ILE
- 82%
- 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
(19 across 19 ecosystems)
Alpine:v3.13(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| py3-urllib3 | — | 1.25.9-r0 | — |
Alpine:v3.14(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| py3-urllib3 | — | 1.25.9-r0 | — |
Alpine:v3.15(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| py3-urllib3 | — | 1.25.9-r0 | — |
Alpine:v3.16(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| py3-urllib3 | — | 1.25.9-r0 | — |
Alpine:v3.17(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| py3-urllib3 | — | 1.25.9-r0 | — |
Alpine:v3.18(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| py3-urllib3 | — | 1.25.9-r0 | — |
Alpine:v3.19(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| py3-urllib3 | — | 1.25.9-r0 | — |
Alpine:v3.20(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| py3-urllib3 | — | 1.25.9-r0 | — |
Alpine:v3.21(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| py3-urllib3 | — | 1.25.9-r0 | — |
Alpine:v3.22(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| py3-urllib3 | — | 1.25.9-r0 | — |
Alpine:v3.23(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| py3-urllib3 | — | 1.25.9-r0 | — |
Alpine:v3.24(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| py3-urllib3 | — | 1.25.9-r0 | — |
Debian:10(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| python-urllib3 | 1.24.1-1 | 1.24.1-1+deb10u1 | — |
Debian:11(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| python-urllib3 | — | 1.25.9-1 | — |
Debian:12(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| python-urllib3 | — | 1.25.9-1 | — |
Debian:13(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| python-urllib3 | — | 1.25.9-1 | — |
Debian:14(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| python-urllib3 | — | 1.25.9-1 | — |
Debian:9(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| python-urllib3 | 1.19.1-1 | 1.19.1-1+deb9u1 | — |
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 5× in last 7d / 22× 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.
Showing the most recent 100 of 143 total refreshes for this CVE.
- 2026-09-18 19:23 UTCEPSS rescore
- 2026-09-17 19:22 UTCEPSS rescore
- 2026-09-16 14:04 UTCEPSS rescore
- 2026-09-15 03:06 UTCEPSS rescore
- 2026-09-12 14:57 UTCEPSS rescore
- 2026-09-11 09:32 UTCEPSS rescore
- 2026-09-08 21:56 UTCEPSS rescore
- 2026-09-07 15:57 UTCEPSS rescore
- 2026-09-06 13:44 UTCEPSS rescore
- 2026-09-05 15:24 UTCEPSS rescore
- 2026-09-04 13:57 UTCEPSS rescore
- 2026-09-04 05:03 UTCEPSS rescore
- 2026-09-02 14:08 UTCEPSS rescore
- 2026-09-01 05:08 UTCOSV refresh
- 2026-09-01 03:32 UTCEPSS rescore
- 2026-08-30 19:14 UTCEPSS rescore
- 2026-08-30 01:18 UTCEPSS rescore
- 2026-08-27 14:21 UTCEPSS rescore
- 2026-08-26 14:42 UTCEPSS rescore
- 2026-08-25 13:45 UTCEPSS rescore
- 2026-08-21 23:45 UTCEPSS rescore
- 2026-08-20 22:52 UTCEPSS rescore
- 2026-08-19 17:00 UTCEPSS rescore
- 2026-08-18 13:44 UTCEPSS rescore
- 2026-08-17 13:43 UTCEPSS rescore
Show 75 moreShow fewer
- 2026-08-16 14:52 UTCEPSS rescore
- 2026-08-16 02:11 UTCEPSS rescore
- 2026-08-15 04:37 UTCOSV refresh
- 2026-08-15 01:26 UTCEPSS rescore
- 2026-08-13 21:57 UTCEPSS rescore
- 2026-08-12 13:47 UTCEPSS rescore
- 2026-08-09 13:43 UTCEPSS rescore
- 2026-08-08 16:33 UTCEPSS rescore
- 2026-08-07 16:23 UTCEPSS rescore
- 2026-08-06 13:43 UTCEPSS rescore
- 2026-08-04 15:06 UTCEPSS rescore
- 2026-08-04 10:34 UTCEPSS rescore
- 2026-08-02 02:23 UTCEPSS rescore
- 2026-08-01 04:12 UTCEPSS rescore
- 2026-07-30 17:21 UTCOSV refresh
- 2026-07-30 16:25 UTCEPSS rescore
- 2026-07-30 01:27 UTCEPSS rescore
- 2026-07-28 15:33 UTCEPSS rescore
- 2026-07-26 14:51 UTCEPSS rescore
- 2026-07-25 14:15 UTCEPSS rescore
- 2026-07-24 14:14 UTCEPSS rescore
- 2026-07-23 14:15 UTCEPSS rescore
- 2026-07-23 14:15 UTCEPSS rescore
- 2026-07-23 01:51 UTCEG score recompute
- 2026-07-22 22:37 UTCEG score recompute
- 2026-07-22 14:05 UTCEPSS rescore
- 2026-07-21 15:22 UTCEPSS rescore
- 2026-07-21 15:22 UTCEPSS rescore
- 2026-07-20 17:04 UTCEPSS rescore
- 2026-07-20 17:04 UTCEPSS rescore
- 2026-07-19 14:28 UTCEPSS rescore
- 2026-07-19 14:28 UTCEPSS rescore
- 2026-07-19 02:26 UTCEPSS rescore
- 2026-07-19 02:26 UTCEPSS rescore
- 2026-07-16 16:59 UTCEPSS rescore
- 2026-07-15 16:55 UTCEPSS rescore
- 2026-07-15 16:55 UTCEPSS rescore
- 2026-07-15 01:57 UTCEPSS rescore
- 2026-07-13 22:27 UTCEPSS rescore
- 2026-07-13 22:27 UTCEPSS rescore
- 2026-07-13 06:10 UTCEPSS rescore
- 2026-07-13 06:10 UTCEPSS rescore
- 2026-07-13 02:07 UTCOSV refresh
- 2026-07-12 05:44 UTCEPSS rescore
- 2026-07-11 08:25 UTCEPSS rescore
- 2026-07-11 08:25 UTCEPSS rescore
- 2026-07-09 19:07 UTCEPSS rescore
- 2026-07-08 15:12 UTCEPSS rescore
- 2026-07-07 13:43 UTCEPSS rescore
- 2026-07-06 16:25 UTCEPSS rescore
- 2026-07-06 16:25 UTCEPSS rescore
- 2026-07-06 02:21 UTCEPSS rescore
- 2026-07-06 02:21 UTCEPSS rescore
- 2026-07-04 06:29 UTCEPSS rescore
- 2026-07-04 06:29 UTCEPSS rescore
- 2026-06-30 23:20 UTCEPSS rescore
- 2026-06-30 23:20 UTCEPSS rescore
- 2026-06-29 14:04 UTCEPSS rescore
- 2026-06-28 04:54 UTCEPSS rescore
- 2026-06-28 04:54 UTCEPSS rescore
- 2026-06-27 03:06 UTCEPSS rescore
- 2026-06-27 03:06 UTCEPSS rescore
- 2026-06-25 13:48 UTCEPSS rescore
- 2026-06-24 14:03 UTCEPSS rescore
- 2026-06-24 14:03 UTCEPSS rescore
- 2026-06-24 11:50 UTCOSV refresh
- 2026-06-23 21:31 UTCEPSS rescore
- 2026-06-23 21:31 UTCEPSS rescore
- 2026-06-21 14:54 UTCEPSS rescore
- 2026-06-21 14:54 UTCEPSS rescore
- 2026-06-21 01:57 UTCEPSS rescore
- 2026-06-21 01:57 UTCEPSS rescore
- 2026-06-19 19:23 UTCEPSS rescore
- 2026-06-18 17:50 UTCEPSS rescore
- 2026-06-17 17:50 UTCEPSS rescore
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?
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