Bug 2456335 (CVE-2026-33810)

Summary: CVE-2026-33810 crypto/x509: golang: Go crypto/x509: Certificate validation bypass due to incorrect DNS constraint application
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: aazores, abarbaro, abrianik, akostadi, akoudelk, alcohan, alebedev, alizardo, amasferr, anjoseph, anpicker, ansmith, anthomas, bbrownin, bdettelb, bparees, chfoley, ckandaga, cmah, crizzo, dhanak, dmayorov, doconnor, drosa, dschmidt, dsimansk, dymurray, eaguilar, ebaron, eborisov, eglynn, ehelms, erezende, fdeutsch, ggainey, ggrzybek, gparvin, hasun, ibolton, jbalunas, jburrell, jcantril, jchui, jeder, jfula, jhe, jjoyce, jkoehler, jlanda, jlledo, jmatthew, jmontleo, jolong, jowilson, jprabhak, jpretori, jraez, jschluet, juwatts, kingland, kshier, ktsao, kverlaen, lball, lbragsta, lchilton, lgamliel, lhh, lphiri, manissin, mbocek, mburns, mgarciac, mhulan, mnovotny, mrunge, mwringe, nboldt, ngough, nmoumoul, nyancey, oaljalju, ometelka, oramraz, osousa, pahickey, pantinor, parichar, pcreech, peholase, pgaikwad, pjindal, psrna, ptisnovs, pvasanth, rchan, rfreiman, rgodfrey, rhaigner, rhel-process-autobot, rjohnson, rojacob, sakbas, sausingh, sdawley, sfeifer, simaishi, slucidi, smallamp, smcdonal, smullick, sseago, stcannon, stirabos, swoodman, syedriko, tasato, teagle, thason, tmalecek, tsedmik, veshanka, vimartin, vkarehfa, watson-tool-maintainers, wenshen, whayutin, wtam, xdharmai, yguenane
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the `crypto/x509` package within Go (golang). When verifying a certificate chain, excluded DNS (Domain Name System) constraints are not correctly applied to wildcard DNS Subject Alternative Names (SANs) if the case of the SAN differs from the constraint. This oversight could allow an attacker to bypass certificate validation, potentially leading to the acceptance of a malicious certificate that should have been rejected. This issue specifically impacts the validation of trusted certificate chains.
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Last Closed: Type: ---
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Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2456853    
Bug Blocks:    

Description OSIDB Bzimport 2026-04-08 02:01:32 UTC
When verifying a certificate chain containing excluded DNS constraints, these constraints are not correctly applied to wildcard DNS SANs which use a different case than the constraint. This only affects validation of otherwise trusted certificate chains, issued by a root CA in the VerifyOptions.Roots CertPool, or in the system certificate pool.

Comment 4 errata-xmlrpc 2026-05-06 21:10:30 UTC
This issue has been addressed in the following products:

  Cryostat 4 on RHEL 9

Via RHSA-2026:14391 https://access.redhat.com/errata/RHSA-2026:14391

Comment 6 errata-xmlrpc 2026-05-19 16:07:32 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:19135 https://access.redhat.com/errata/RHSA-2026:19135

Comment 7 errata-xmlrpc 2026-05-19 16:09:06 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:19144 https://access.redhat.com/errata/RHSA-2026:19144

Comment 8 errata-xmlrpc 2026-05-19 21:39:15 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:19353 https://access.redhat.com/errata/RHSA-2026:19353

Comment 9 errata-xmlrpc 2026-05-20 16:41:06 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10.0 Extended Update Support

Via RHSA-2026:19719 https://access.redhat.com/errata/RHSA-2026:19719

Comment 10 errata-xmlrpc 2026-05-20 16:48:36 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Extended Update Support

Via RHSA-2026:19721 https://access.redhat.com/errata/RHSA-2026:19721

Comment 11 errata-xmlrpc 2026-05-20 16:53:31 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:19720 https://access.redhat.com/errata/RHSA-2026:19720