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[SECURITY ADVISORY] curl: CVE-2023-27537: HSTS double-free
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From: Daniel Stenberg via curl-users <curl-users_at_lists.haxx.se>
Date: Mon, 20 Mar 2023 08:26:17 +0100 (CET)
CVE-2023-27537: HSTS double-free
================================
Project curl Security Advisory, March 20th 2023 -
[Permalink](https://curl.se/docs/CVE-2023-27537.html)
VULNERABILITY
-------------
libcurl supports sharing HSTS data between separate "handles". This sharing was
introduced without considerations for do this sharing across separate threads
but there was no indication of this fact in the documentation.
Due to missing mutexes or thread locks, two threads sharing the same HSTS data
could end up doing a double-free or use-after-free.
We are not aware of any exploit of this flaw.
INFO
Date: Mon, 20 Mar 2023 08:26:17 +0100 (CET)
CVE-2023-27537: HSTS double-free
================================
Project curl Security Advisory, March 20th 2023 -
[Permalink](https://curl.se/docs/CVE-2023-27537.html)
VULNERABILITY
-------------
libcurl supports sharing HSTS data between separate "handles". This sharing was
introduced without considerations for do this sharing across separate threads
but there was no indication of this fact in the documentation.
Due to missing mutexes or thread locks, two threads sharing the same HSTS data
could end up doing a double-free or use-after-free.
We are not aware of any exploit of this flaw.
INFO
---- This feature was not implemented to support sharing between threads. That is still left for future improvements. The fix for this issue is therefore a documentation update clarifying that sharing HSTS between threads is not expected to work. CVE-2023-27537 was introduced in [commit 076a2f629119222a](https://github.com/curl/curl/commit/076a2f629119222a), shipped in curl 7.88.0. CWE-415: Double Free Severity: Low Severity is set to Low because - Not widely used functionality - The timing necessary to trigger this has to match fairly exact - Exploitation this for anything but denial of service is difficult AFFECTED VERSIONS ----------------- - Affected versions: curl 7.88.0 to and including 7.88.1 - Not affected versions: curl < 7.88.0 and curl >= 8.0.0 libcurl is used by many applications, but not always advertised as such! THE SOLUTION ------------ A [fix for CVE-2023-27537](https://github.com/curl/curl/commit/dca4cdf071be0) RECOMMENDATIONS -------------- A - Do not share HSTS data between threads TIMELINE -------- This issue was reported to the curl project on March 8 2023. We contacted distros_at_openwall on March 13, 2023. curl 8.0.0 was released on March 20 2023, coordinated with the publication of this advisory. CREDITS ------- - Reported-by: Hiroki Kurosawa - Patched-by: Daniel Stenberg Thanks a lot! -- / daniel.haxx.se | Commercial curl support up to 24x7 is available! | Private help, bug fixes, support, ports, new features | https://curl.se/support.html -- Unsubscribe: https://lists.haxx.se/mailman/listinfo/curl-users Etiquette: https://curl.se/mail/etiquette.htmlReceived on 2023-03-20