CVE-2021-23336: The package python/cpython from 0 and before 3.6.13, from 3.7.0 and before 3.7.10, from 3.8.0 and before 3.8.8, from 3.9.0 and before 3.9.2
Noroxi assessment
Priority: Monitor (action score 35/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 40.7% (FIRST EPSS); higher than 98.6% of all records.
- Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. Special conditions such as timing or configuration are required.
- Fixed version: CBL Mariner 1.0 ARM 2.7.18-6, 3.7.10-3; CBL Mariner 1.0 x64 2.7.18-6, 3.7.10-3.
- Mentioned 2 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Low priority for now. Upgrade to CBL Mariner 1.0 ARM 2.7.18-6, 3.7.10-3; CBL Mariner 1.0 x64 2.7.18-6, 3.7.10-3 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
The package python/cpython from 0 and before 3.6.13, from 3.7.0 and before 3.7.10, from 3.8.0 and before 3.8.8, from 3.9.0 and before 3.9.2 are vulnerable to Web Cache Poisoning via urllib.parse.parse_qsl and urllib.parse.parse_qs by using a vector called parameter cloaking. When the attacker can separate query parameters using a semicolon (;), they can cause a difference in the interpretation of the request between the proxy (running with default configuration) and the server. This can result in malicious requests being cached as completely safe ones, as the proxy would usually not see the semicolon as a separator, and therefore would not include it in a cache key of an unkeyed parameter.
- BDU:2021-03763
- ALSA-2021:4151
- ALSA-2021:4162
- DLA-2569-1
- DLA-2619-1
- DLA-2628-1
- DLA-3164-1
- DLA-3575-1
- openSUSE-SU-2021:0435-1
- openSUSE-SU-2024:11279-1
- openSUSE-SU-2024:11283-1
- openSUSE-SU-2024:11285-1
- openSUSE-SU-2024:11286-1
- openSUSE-SU-2024:12089-1
- openSUSE-SU-2024:12910-1
- openSUSE-SU-2024:14037-1
- openSUSE-SU-2024:14109-1
- openSUSE-SU-2024:14434-1
- openSUSE-SU-2025:15713-1
- openSUSE-SU-2026:11589-1
- Published
- Feb 15, 2021
- Updated
- Oct 14, 2026
- EPSS
- 40.7% · 98th percentile
- CWE
- CWE-444
Report tools
Action score
35
Monitor
Low priority for now.
- CVSS
- 23 / 40 · 5.9 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 12 / 30 · 40.7%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 5.9
- CNA · snyk
- 5.9
- agree
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:H/E:P/RL:U/RC:C
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| python | python | cpe:2.3:a:python:python |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
| netapp | cloud backup | cpe:2.3:a:netapp:cloud_backup |
| netapp | inventory collect tool | cpe:2.3:a:netapp:inventory_collect_tool |
| netapp | ontap select deploy administration utility | cpe:2.3:a:netapp:ontap_select_deploy_administration_utility |
| netapp | snapcenter | cpe:2.3:a:netapp:snapcenter |
| djangoproject | django | cpe:2.3:a:djangoproject:django |
| oracle | communications offline mediation controller | cpe:2.3:a:oracle:communications_offline_mediation_controller |
| oracle | communications pricing design center | cpe:2.3:a:oracle:communications_pricing_design_center |
| oracle | enterprise manager ops center | cpe:2.3:a:oracle:enterprise_manager_ops_center |
| oracle | zfs storage appliance | cpe:2.3:o:oracle:zfs_storage_appliance |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- debian debian linux9.0
- djangoproject django3.0 and later · before 3.0.13
- djangoproject django2.2 and later · before 2.2.19
- djangoproject django3.1 and later · before 3.1.7
- fedoraproject fedora32
- fedoraproject fedora33
- fedoraproject fedora34
- netapp cloud backupall versions
- netapp inventory collect toolall versions
- netapp ontap select deploy administration utilityall versions
- netapp snapcenterall versions
- oracle communications offline mediation controller12.0.0.3.0
- oracle communications pricing design center12.0.0.3.0
- oracle enterprise manager ops center12.4.0.0
- oracle zfs storage appliance8.8
- python python3.9.0 and later · before 3.9.2
- python python3.8.0 and later · before 3.8.8
- python python3.7.0 and later · before 3.7.10
- python pythonbefore 3.6.13
Versions reported by the vendor
Affected version ranges reported by the assigning authority (snyk). Independent of NVD's CPE analysis and usually ahead of it.
n/a python/cpython
- before unspecifiedaffected
- unspecified and later · before 3.6.13affected
- 3.7.0 and later · before unspecifiedaffected
- unspecified and later · before 3.7.10affected
- 3.8.0 and later · before unspecifiedaffected
- unspecified and later · before 3.8.8affected
- 3.9.0 and later · before unspecifiedaffected
- unspecified and later · before 3.9.2affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:8 | babel | before 2.5.1-10.module_el8.6.0+2781+fed64c13 | 2.5.1-10.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python-nose-docs | before 1.3.7-31.module_el8.5.0+2569+5c5719bc | 1.3.7-31.module_el8.5.0+2569+5c5719bc |
| AlmaLinux:8 | python-nose-docs | before 1.3.7-31.module_el8.6.0+2781+fed64c13 | 1.3.7-31.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python-psycopg2-doc | before 2.7.5-7.module_el8.6.0+2781+fed64c13 | 2.7.5-7.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python-sqlalchemy-doc | before 1.3.2-2.module_el8.6.0+2781+fed64c13 | 1.3.2-2.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python-sqlalchemy-doc | before 1.3.2-2.module_el8.5.0+2569+5c5719bc | 1.3.2-2.module_el8.5.0+2569+5c5719bc |
| AlmaLinux:8 | python2-attrs | before 17.4.0-10.module_el8.6.0+2781+fed64c13 | 17.4.0-10.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-babel | before 2.5.1-10.module_el8.6.0+2781+fed64c13 | 2.5.1-10.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-backports | before 1.0-16.module_el8.6.0+2781+fed64c13 | 1.0-16.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-backports-ssl_match_hostname | before 3.5.0.1-12.module_el8.6.0+2781+fed64c13 | 3.5.0.1-12.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-bson | before 3.7.0-1.module_el8.6.0+2781+fed64c13 | 3.7.0-1.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-chardet | before 3.0.4-10.module_el8.6.0+2781+fed64c13 | 3.0.4-10.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-coverage | before 4.5.1-4.module_el8.6.0+2781+fed64c13 | 4.5.1-4.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-Cython | before 0.28.1-7.module_el8.6.0+2781+fed64c13 | 0.28.1-7.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-dns | before 1.15.0-10.module_el8.6.0+2781+fed64c13 | 1.15.0-10.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-docs | before 2.7.16-2.module_el8.6.0+2781+fed64c13 | 2.7.16-2.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-docs-info | before 2.7.16-2.module_el8.6.0+2781+fed64c13 | 2.7.16-2.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-docutils | before 0.14-12.module_el8.6.0+2781+fed64c13 | 0.14-12.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-funcsigs | before 1.0.2-13.module_el8.6.0+2781+fed64c13 | 1.0.2-13.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-idna | before 2.5-7.module_el8.6.0+2781+fed64c13 | 2.5-7.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-ipaddress | before 1.0.18-6.module_el8.6.0+2781+fed64c13 | 1.0.18-6.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-jinja2 | before 2.10-9.module_el8.6.0+2781+fed64c13 | 2.10-9.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-markupsafe | before 0.23-19.module_el8.6.0+2781+fed64c13 | 0.23-19.module_el8.6.0+2781+fed64c13 |
| AlmaLinux:8 | python2-mock | before 2.0.0-13.module_el8.6.0+2781+fed64c13 | 2.0.0-13.module_el8.6.0+2781+fed64c13 |
+96
Same product
python: all recordsOther highest-scoring records for the same primary product.
- CVE-2016-5636Integer overflow in the get_data function in zipimport.c in CPython (aka Python) before 2.7.12, 3.x before 3.4.5, and 3.5.x before 3.5.2 all47Plan
- CVE-2007-4559Directory traversal vulnerability in the (1) extract and (2) extractall functions in the tarfile module in Python allows user-assisted remot47Plan
- CVE-2021-3177Python 3.x through 3.9.1 has a buffer overflow in PyCArg_repr in _ctypes/callproc.c, which may lead to remote code execution in certain Pyth46Plan
Published before and after this one in the same product
- ← EarlierCVE-2020-26116Sep 27, 2020 · 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 attack30Monitor
- ← EarlierCVE-2020-27619Oct 22, 2020 · In Python 3 through 3.9.0, the Lib/test/multibytecodec_support.py CJK codec tests call eval() on content retrieved via HTTP.42Plan
- Later →CVE-2021-32052May 6, 2021 · In Django 2.2 before 2.2.22, 3.1 before 3.1.10, and 3.2 before 3.2.2 (with Python 3.9.5+), URLValidator does not prohibit newlines and tabs 25Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| CBL Mariner 1.0 ARM | 2.7.18-6 · python2 | Microsoft (MSRC) |
| CBL Mariner 1.0 ARM | 3.7.10-3 · python3 | Microsoft (MSRC) |
| CBL Mariner 1.0 x64 | 2.7.18-6 · python2 | Microsoft (MSRC) |
| CBL Mariner 1.0 x64 | 3.7.10-3 · python3 | Microsoft (MSRC) |
| almalinux:babel | 2.5.1-10.module_el8.6.0+2781+fed64c13 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python-nose-docs | 1.3.7-31.module_el8.6.0+2781+fed64c13 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python-psycopg2-doc | 2.7.5-7.module_el8.6.0+2781+fed64c13 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python-sqlalchemy-doc | 1.3.2-2.module_el8.6.0+2781+fed64c13 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python2-attrs | 17.4.0-10.module_el8.6.0+2781+fed64c13 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python2-babel | 2.5.1-10.module_el8.6.0+2781+fed64c13 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python2-backports | 1.0-16.module_el8.6.0+2781+fed64c13 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python2-backports-ssl_match_hostname | 3.5.0.1-12.module_el8.6.0+2781+fed64c13 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python2-bson | 3.7.0-1.module_el8.6.0+2781+fed64c13 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python2-chardet | 3.0.4-10.module_el8.6.0+2781+fed64c13 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python2-Cython | 0.28.1-7.module_el8.6.0+2781+fed64c13 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:python2-PyMySQL | 0.8.0-10.module_el8.6.0+2781+fed64c13 · AlmaLinux:8 | Package registry (OSV) |
| alpine:py3-django | 3.1.7-r0 · Alpine:v3.13 | Package registry (OSV) |
| alpine:python3 | 3.8.8-r0 · Alpine:v3.12 | Package registry (OSV) |
| debian:pypy3 | 7.3.3+dfsg-3 · Debian:12 | Package registry (OSV) |
| debian:python-django | 2:2.2.19-1 · Debian:12 | Package registry (OSV) |
| debian:python2.7 | 2.7.13-2+deb9u5 · Debian:9 | Package registry (OSV) |
| debian:python3.5 | 3.5.3-1+deb9u4 · Debian:9 | Package registry (OSV) |
| opensuse:python | 2.7.18-lp152.3.15.1 · openSUSE:Leap 15.2 | Package registry (OSV) |
| opensuse:python-base | 2.7.18-lp152.3.15.1 · openSUSE:Leap 15.2 | Package registry (OSV) |
| opensuse:python-doc | 2.7.18-lp152.3.15.1 · openSUSE:Leap 15.2 | Package registry (OSV) |
| opensuse:python-w3lib | 1.22.0-2.4 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:python310 | 3.10.0rc1-4.2 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:python311 | 3.11.0b1-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:python312 | 3.12.0a7-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:python313 | 3.13.0~b3-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
+40
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-21-0772 · Sep 23, 2021(RedHat Güvenlik Zafiyeti)
- TR-21-0331 · Apr 21, 2021(Oracle Güvenlik Uyarısı Yayınladı)
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- A user must open a link or visit a page.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- none
- Integrity
- low · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- Low
- Availability impact
- High
Weakness class (CWE)
CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (19 more)Show less
- www.openwall.com/lists/oss-security/2021/05/01/2
- github.com/python/cpython/pull/24297
- lists.apache.org/thread.html/ra8ce70088ba291f358e077cafdb14d174b7a1ce9a9d86d1b332d6367%40%3Cusers.airflow.apache.org%3E
- lists.apache.org/thread.html/rc005f4de9d9b0ba943ceb8ff5a21a5c6ff8a9df52632476698d99432%40%3Cannounce.apache.org%3E
- lists.apache.org/thread.html/rf9fa47ab66495c78bb4120b0754dd9531ca2ff0430f6685ac9b07772%40%3Cdev.mina.apache.org%3E
- lists.debian.org/debian-lts-announce/2021/02/msg00030.html
- lists.debian.org/debian-lts-announce/2021/04/msg00005.html
- lists.debian.org/debian-lts-announce/2021/04/msg00015.html
- lists.debian.org/debian-lts-announce/2023/09/msg00022.html
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3EPYWWFDV22CJ5AOH5VCE72DOASZZ255/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3YKKDLXL3UEZ3J426C2XTBS63AHE46SM/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/46N6A52EGSXHJYCZWVMBJJIH4NWIV2B5/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FONHJIOZOFD7CD35KZL6SVBUTMBPGZGA/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HCQTCSP6SCVIYNIRUJC5X7YBVUHPLSC4/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HZTM7KLHFCE3LWSEVO2NAFLUHMGYMCRY/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IHQDU7NXA7EWAE4W7VO6MURVJIULEPPR/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KJXCMHLY7H3FIYLE4OKDYUILU2CCRUCZ/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LVNH6Z24IG3E67ZCQGGJ46FZB4XFLQNZ/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MNUN5SOMFL2BBKP6ZAICIIUPQKZDMGYO/
Vendor advisories and official records. Exploit/PoC links are deliberately left out.