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🛡️ CVE-2023-45803 — fedora

🟡 CVSS 4.2 — Medium ✅ No Known Exploit CWE-200 NVD
4.2
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

urllib3's request body not stripped after redirect from 303 status changes request method to GET

urllib3 previously wouldn't remove the HTTP request body when an HTTP redirect response using status 303 "See Other" 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 the behavior of removing the request body 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.

From [RFC 9110 Section 9.3.1](https://www.rfc-editor.org/rfc/rfc9110.html#name-get):

> A client SHOULD NOT generate content in a GET request unless it is made directly to an origin server that has previously indicated, in or out of band, that such a request has a purpose and will be adequately supported.

Affected usages

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:

  • If you're using urllib3 and submitting sensitive information in the HTTP request body (such as form data or JSON)
  • The origin service is compromised and starts redirecting using 303 to a malicious peer or the redirected-to service becomes compromised.

Remediation

You can remediate this vulnerability with any of the following steps:

  • Upgrade to a patched version of urllib3 (v1.26.18 or v2.0.7)
  • Disable redirects for services that you aren't expecting to respond with redirects with redirects=False.
  • Disable automatic redirects with redirects=False and handle 303 redirects manually by stripping the HTTP request body.

How this vulnerability can be exploited

This issue can be reached from an adjacent network, attack complexity is high, an attacker needs administrative privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity none, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:A/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N

  • Attack vector: Adjacent network — the attacker has to sit on the same local or logical network.
  • Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
  • Privileges required: High — administrative rights are needed first.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: None.
  • Availability impact: None.

Weakness class

CVE-2023-45803 is classified as CWE-200: Exposure of Sensitive Information. Information that should stay internal is disclosed to someone who is not authorised to see it.

Affected software

CVE-2023-45803 is recorded against 2 packages.

  • fedora
  • urllib3 (from 2.0.0 up to 1.26.18)

Timeline and source

Published on 17 October 2023 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com
github.com
lists.fedoraproject.org
lists.fedoraproject.org
lists.fedoraproject.org
www.rfc-editor.org
github.com
github.com
lists.debian.org
lists.fedoraproject.org
lists.fedoraproject.org
lists.fedoraproject.org
www.rfc-editor.org

Other advisories for this package

fedora has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-200: Exposure of Sensitive Information) in other software:

CVE-2023-45803 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity MEDIUM
CVSS Score 4.2
CVSS Vector CVSS:3.1/AV:A/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N
CWE CWE-200
Public Exploit ✅ No
Source NVD
Published 2023-10-17
Updated 2026-08-20
Modified 2026-06-17

Affected Packages

Software From version Fixed in
fedora — —
urllib3 2.0.0 1.26.18

References

Similar Threats

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