From 5d178de986ee124a8ec88f252769488d6644decb Mon Sep 17 00:00:00 2001 From: Daniel Stenberg Date: Tue, 2 Jun 2026 17:40:48 +0200 Subject: [PATCH] hsts.md: mention multiple curl invokes effect Reported-by: zhanhb on github Ref: #21847 Closes #21851 --- docs/cmdline-opts/hsts.md | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/docs/cmdline-opts/hsts.md b/docs/cmdline-opts/hsts.md index f99b91c281..7653c65cd5 100644 --- a/docs/cmdline-opts/hsts.md +++ b/docs/cmdline-opts/hsts.md @@ -18,7 +18,9 @@ Example: Enable HSTS for the transfer. If the filename points to an existing HSTS cache file, that is used. After a completed transfer, the cache is saved to the -filename again if it has been modified. +filename again if it has been modified. If you run multiple curl invokes at +the same time using the same HSTS cache file, they might interfere with each +other in possibly undesired ways. If curl is told to use `http://` for a transfer involving a hostname that exists in the HSTS cache, it upgrades the transfer to use HTTPS. Each HSTS