Know every vulnerabilitybefore it knows you.
DevGuard continuously monitors your dependencies and alerts you when CVEs like this one affect your stack — with real-time threat intelligence built for developers.
PYSEC-2026-1999
urllib3urllib3 handles redirects and retries using the same mechanism, which is controlled by the Retry object. The most common way to disable redirects is at the request level, as follows:
resp = urllib3.request("GET", "https://httpbin.org/redirect/1", redirect=False)
print(resp.status)
# 302
However, it is also possible to disable redirects, for all requests, by instantiating a PoolManager and specifying retries in a way that disable redirects:
import urllib3
http = urllib3.PoolManager(retries=0) # should raise MaxRetryError on redirect
http = urllib3.PoolManager(retries=urllib3.Retry(redirect=0)) # equivalent to the above
http = urllib3.PoolManager(retries=False) # should return the first response
resp = http.request("GET", "https://httpbin.org/redirect/1")
However, the retries parameter is currently ignored, which means all the above examples don't disable redirects.
Affected usages
Passing retries on PoolManager instantiation to disable redirects or restrict their number.
By default, requests and botocore users are not affected.
Impact
Redirects are often used to exploit SSRF vulnerabilities. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable.
Remediation
You can remediate this vulnerability with the following steps:
- Upgrade to a patched version of urllib3. If your organization would benefit from the continued support of urllib3 1.x, please contact sethmichaellarson@gmail.com to discuss sponsorship or contribution opportunities.
- Disable redirects at the
request()level instead of thePoolManager()level.
The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
Browse More
Continuously monitor your dependencies and get alerted when vulnerabilities like this one affect your stack.
Checkout DevGuard