CVE-2023-45803 | Request body not stripped after redirect in urllib3

urllib3 is a user-friendly HTTP client library for Python. urllib3 previously wouldn't remove the HTTP request body when an HTTP redirect response using status 301, 302, or 303 after the request had its method changed from one that could accept a request body (like `POST`) to `GET` as is required by HTTP RFCs. Although this behavior is not specified in the section for redirects, it can be inferred by piecing together information from different sections and we have observed the behavior in other major HTTP client implementations like curl and web browsers. Because the vulnerability requires a previously trusted service to become compromised in order to have an impact on confidentiality we believe the exploitability of this vulnerability is low. Additionally, many users aren't putting sensitive data in HTTP request bodies, if this is the case then this vulnerability isn't exploitable. Both of the following conditions must be true to be affected by this vulnerability: 1. Using urllib3 and submitting sensitive information in the HTTP request body (such as form data or JSON) and 2. The origin service is compromised and starts redirecting using 301, 302, or 303 to a malicious peer or the redirected-to service becomes compromised. This issue has been addressed in versions 1.26.18 and 2.0.7 and users are advised to update to resolve this issue. Users unable to update should disable redirects for services that aren't expecting to respond with redirects with `redirects=False` and disable automatic redirects with `redirects=False` and handle 301, 302, and 303 redirects manually by stripping the HTTP request body.

Published: 2023-10-17 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-45803 is rated Low Risk (31.7/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.54%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-45803

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.05% 0.54% +0.49%
2 2025-11-21 0.16% 0.05% -0.11%
3 2025-11-18 — 0.16% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-45803

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.2 3.1 MEDIUM
CVSS:3.1/AV:A/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 0.5 3.6 [email protected]
4.2 3.1 MEDIUM
CVSS:3.1/AV:A/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 0.5 3.6 [email protected]

Weakness enumeration for CVE-2023-45803

GitHub Security Advisory for CVE-2023-45803

GHSA-g4mx-q9vg-27p4 · Severity: medium · Ecosystem: pip — urllib3's request body not stripped after redirect from 303 status changes request method to GET

OS Trackers for CVE-2023-45803

vendor priority summary link
alpine medium CVE-2023-45803: 1 source package rows (py3-urllib3); 22 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 7, open 15. https://security.alpinelinux.org/vuln/CVE-2023-45803
debian not yet assigned CVE-2023-45803 not yet assigned priority: Debian including 1 source packages (python-urllib3), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-45803
redhat medium — https://access.redhat.com/security/cve/CVE-2023-45803
suse medium CVE-2023-45803 severity moderate: SUSE including 398 source package names (5.0.0-beta1.2.122:python3-urllib3-1.25.10-150300.4.9.1, 5.0.0-beta1.2.90:python3-urllib3-1.25.10-150300.4.9.1, …), 704 product×package rows across 311 product lines (Container bci/kiwi, Container suse/manager/4.3/proxy-tftpd, … (311 product lines)): Fixed 517, Known Affected 187. https://www.suse.com/security/cve/CVE-2023-45803/
ubuntu medium CVE-2023-45803 medium priority: Ubuntu including 2 source packages (python-pip, python-urllib3), 24 status rows across 12 suites (bionic, focal, jammy, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): released 14, not-affected 6, needed 2, ignored 1, needs-triage 1. https://ubuntu.com/security/CVE-2023-45803

Affected software / configurations for CVE-2023-45803

Vendor Product Version Raw CPE
python urllib3 < 1.26.18 cpe:2.3:a:python:urllib3:*:*:*:*:*:*:*:*
python urllib3 >= 2.0.0, < 2.0.7 cpe:2.3:a:python:urllib3:*:*:*:*:*:*:*:*
fedoraproject fedora 38 cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*

References for CVE-2023-45803

cvelogic Threat Intelligence