Bug 1964904 (CVE-2021-22897)

Summary:	CVE-2021-22897 curl: Cipher settings shared for all connections when using schannel TLS backed
Product:	[Other] Security Response	Reporter:	msiddiqu
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	amctagga, andrew.slice, anharris, bniver, bodavis, dbhole, erik-fedora, flucifre, gmeno, hhorak, hvyas, jorton, kanderso, kaycoth, kdudka, luhliari, lvaleeva, mbenjamin, mhackett, mike, msekleta, omajid, paul, rwagner, sostapov, svashisht, vereddy, vmugicag
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	curl 7.77.0	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in curl where libcurl lets applications specify which specific TLS ciphers to use in transfers, using the option called CURLOPT_SSL_CIPHER_LIST. The cipher selection is used for the TLS negotiation when a transfer is done involving any of the TLS based transfer protocols libcurl supports, such as HTTPS, FTPS, IMAPS, POP3S, SMTPS, etc. Due to a mistake in the code, the selected cipher set was stored in a single "static" variable in the library, which contains a side-effect that if an application sets up multiple concurrent transfers, the last one that sets the ciphers will accidentally control the set used by all transfers. In a worst-case scenario, this weakens transport security significantly. The highest threat from this vulnerability is to confidentiality.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-06-09 15:05:50 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	1964912

Description msiddiqu 2021-05-26 10:04:24 UTC

libcurl lets applictions specify which specific TLS ciphers to use in transfers, using the option called CURLOPT_SSL_CIPHER_LIST. The cipher selection is used for the TLS negotation when a transfer is done involving any of the TLS based transfer protocols libcurl supports, such as HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. Due to a mistake in the code, the selected cipher set was stored in a single "static" variable in the library, which has the surprising side-effect that if an application sets up multiple concurrent transfers, the last one that sets the ciphers will accidentally control the set used by all transfers. In a worst-case scenario, this weakens transport security significantly.

Comment 1 Tomas Hoger 2021-05-26 11:02:43 UTC

Upstream advisory:

https://curl.se/docs/CVE-2021-22897.html

Upstream commit:

https://github.com/curl/curl/commit/bbb71507b7bab52002f9b1e0880bed6a32834511

Comment 2 Tomas Hoger 2021-05-26 11:05:20 UTC

This issue does not affect the curl packages as shipped in Red Hat products, as it only affects curl versions build to use schannel library as its TLS backend.  The schannel is the native TLS library in Microsoft Windows.

Comment 3 Product Security DevOps Team 2021-06-09 15:05:50 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2021-22897

Comment 4 Tomas Hoger 2021-06-10 21:03:42 UTC

HackerOne report:

https://hackerone.com/reports/1172857