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CVE-2025-13836

Excessive read buffering DoS in http.client

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 3.10.20, 3.11.15, 3.12.13, 3.13.11, 3.14.1, and 1 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

When reading an HTTP response from a server, if no read amount is specified, the default behavior will be to use Content-Length. This allows a malicious server to cause the client to read large amounts of data into memory, potentially causing OOM or other DoS.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • Python Software Foundation CPython

    fixed in 3.10.20; From 3.11.0 · fixed in 3.11.15; From 3.12.0 · fixed in 3.12.13; From 3.13.0 · fixed in 3.13.11; From 3.14.0 · fixed in 3.14.1; From 3.15.0a1 · fixed in 3.15.0a3

References 9

GitHub · python/cpython

mail.python.org