Bug 2088544 (CVE-2022-29217)

Summary:	CVE-2022-29217 python-jwt: Key confusion through non-blocklisted public key formats
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Nobody <nobody>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	adudiak, alex, ali.erdinc.koroglu, aoconnor, bbuckingham, bcoca, bcourt, bdettelb, bniver, chousekn, cluster-maint, cmeyers, dmendiza, eglynn, ehelms, fedora, flucifre, gmeno, i, infra-sig, jcammara, jhardy, jjoyce, jobarker, jperrin, jpopelka, jschluet, jsherril, jwong, kaycoth, kevin, kshier, lbragsta, lhh, lzap, mabashia, mbenjamin, mburns, mhackett, mhulan, msuchy, nkinder, nmoumoul, notting, oalbrigt, oblaut, oliver, orabin, pcreech, python-sig, rbean, rchan, rhos-maint, rominf, rpetrell, sdoran, slavek.kabrda, slinaber, smcdonal, sostapov, spotrh, spower, stcannon, suraia, tfister, thalman, tvignaud, vereddy, yguenane
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:	A vulnerability was found in python-jwt. This issue happens when PyJWT supports multiple different JWT signing algorithms. This flaw allows an attacker submitting the JWT token to choose the used signing algorithm, leading to key confusion through non-blocklisted public key formats.	Story Points:	---
Clone Of:		Environment:
Last Closed:		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:	2089226, 2089227, 2089229, 2088546, 2088547, 2088548, 2088549, 2088550, 2088551, 2088552, 2088553, 2088554, 2088555, 2088556, 2088557, 2089144, 2089145, 2089146, 2089147, 2089149, 2089230, 2089231, 2095893, 2095894, 2095895, 2095896, 2095897, 2098090, 2098091, 2098092, 2207679, 2258843
Bug Blocks:	2088545

Description Guilherme de Almeida Suckevicz 2022-05-19 16:44:21 UTC

PyJWT supports multiple different JWT signing algorithms. With JWT, an attacker submitting the JWT token can choose the used signing algorithm.

The PyJWT library requires that the application chooses what algorithms are supported. The application can specify "jwt.algorithms.get_default_algorithms()" to get support for all algorithms. They can also specify a single one of them (which is the usual use case if calling jwt.decode directly. However, if calling jwt.decode in a helper function, all algorithms might be enabled.)

For example, if the user chooses "none" algorithm and the JWT checker supports that, there will be no signature checking. This is a common security issue with some JWT implementations.

PyJWT combats this by requiring that the if the "none" algorithm is used, the key has to be empty. As the key is given by the application running the checker, attacker cannot force "none" cipher to be used.

Similarly with HMAC (symmetric) algorithm, PyJWT checks that the key is not a public key meant for asymmetric algorithm i.e. HMAC cannot be used if the key begins with "ssh-rsa". If HMAC is used with a public key, the attacker can just use the publicly known public key to sign the token and the checker would use the same key to verify.

From PyJWT 2.0.0 onwards, PyJWT supports ed25519 asymmetric algorithm. With ed25519, PyJWT supports public keys that start with "ssh-", for example "ssh-ed25519".

Reference:
https://github.com/jpadilla/pyjwt/security/advisories/GHSA-ffqj-6fqr-9h24

Comment 1 Guilherme de Almeida Suckevicz 2022-05-19 16:50:09 UTC

Created cascadia-code-fonts tracking bugs for this issue:

Affects: fedora-all [bug 2088547]


Created jetbrains-mono-fonts tracking bugs for this issue:

Affects: fedora-all [bug 2088548]


Created openstack-keystone tracking bugs for this issue:

Affects: openstack-rdo [bug 2088555]


Created openstack-mistral tracking bugs for this issue:

Affects: openstack-rdo [bug 2088556]


Created openstack-vitrage tracking bugs for this issue:

Affects: openstack-rdo [bug 2088557]


Created picard tracking bugs for this issue:

Affects: fedora-all [bug 2088549]


Created python-PyGithub tracking bugs for this issue:

Affects: fedora-all [bug 2088550]


Created python-adal tracking bugs for this issue:

Affects: fedora-all [bug 2088551]


Created python-ibm-cloud-sdk-core tracking bugs for this issue:

Affects: fedora-all [bug 2088552]


Created python-jwt tracking bugs for this issue:

Affects: fedora-all [bug 2088546]


Created python-oauthlib tracking bugs for this issue:

Affects: fedora-all [bug 2088553]


Created python-twilio tracking bugs for this issue:

Affects: fedora-all [bug 2088554]

Comment 18 Paul Wouters 2023-01-24 21:12:31 UTC

why was a bug filed for python-twilio for this? It seems a bug in python-jwt and python-twilio has no requires for python-jwt ?

It also seems questionable that other packages listed above like "cascadia-code-fonts" were affected ?

Comment 19 Guilherme de Almeida Suckevicz 2023-01-25 14:17:22 UTC

Hi, if these packages do not depend on python-jwt it's probably a false positive from our scanner tool.

Running the tool again I can't even find these packages on the list anymore.

Feel free to close the tracker bugs related to these packages as NOTABUG.