[3.15] gh-150743: Limit trailer lines and interim responses read by http.client (GH-150741)#152523
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…tp.client (pythonGH-150741) http.client read chunked-response trailer lines and skipped interim (1xx) responses in unbounded loops, so a server streaming either forever would hang the client even with a socket timeout set (data keeps arriving, so the timeout never fires). Trailer lines are now limited to max_response_headers (100 by default) and interim responses to 100; HTTPException is raised past either limit. Follow-up to pythongh-88188 for CVE-2021-3737, which bounded header lines within an interim response but not these two sibling loops. (cherry picked from commit 41cc78a) Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com> --- This issue was reported to us via [GHSA-w4q2-g22w-6fr4](https://github.com/python/cpython/security/advisories/GHSA-w4q2-g22w-6fr4) and was determined not to be high enough severity to handle privately.
This was referenced Jun 28, 2026
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http.client read chunked-response trailer lines and skipped interim (1xx)
responses in unbounded loops, so a server streaming either forever would
hang the client even with a socket timeout set (data keeps arriving, so
the timeout never fires).
Trailer lines are now limited to max_response_headers (100 by default)
and interim responses to 100; HTTPException is raised past either limit.
Follow-up to gh-88188 for CVE-2021-3737, which bounded header lines
within an interim response but not these two sibling loops.
(cherry picked from commit 41cc78a)
Co-authored-by: Gregory P. Smith 68491+gpshead@users.noreply.github.com
This issue was reported to us via GHSA-w4q2-g22w-6fr4 and was determined not to be high enough severity to handle privately.