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CVE-2026-3833— Gnutls: gnutls: policy bypass due to case-sensitive nameconstraints comparison

Quick assessment

Affected

CVE-2026-3833

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Red Hat Enterprise Linux是美国红帽（Red Hat）公司的面向企业用户的Linux操作系统。 Red Hat Enterprise Linux 10存在安全漏洞，该漏洞源于对nameConstraints标签进行大小写敏感比较，可能导致远程攻击者通过构造大小写差异的SAN证书绕过策略限制。

CVSS 6.5 · Medium EPSS 0.56% · P44 Updated Aug 25, 2026

Possible ATT&CK Techniques 1 AI

T1550 · Use Alternate Authentication Material

Affected Version Matrix 33

Vendor	Product	Version Range	Status
None	None	`< 3.8.13`	affected
Red Hat	Red Hat Discovery 2	`1782159791< *`	unaffected
		`1782166952< *`	unaffected
Red Hat	Red Hat Enterprise Linux 10	`0:3.8.10-4.el10_2< *`	unaffected
Red Hat	Red Hat Enterprise Linux 10.0 Extended Update Support	`0:3.8.9-9.el10_0.19< *`	unaffected
Red Hat	Red Hat Enterprise Linux 6	`any`	affected
Red Hat	Red Hat Enterprise Linux 7 Extended Lifecycle Support	`0:3.3.29-9.el7_9.2< *`	unaffected
Red Hat	Red Hat Enterprise Linux 8	`0:3.6.16-8.el8_10.6< *`	unaffected
		`0:3.6.16-8.el8_10.6< *`	unaffected
Red Hat	Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support	`0:3.6.14-10.el8_4.1< *`	unaffected
		`0:4.13-3.el8_4.1< *`	unaffected
Red Hat	Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On	`0:3.6.14-10.el8_4.1< *`	unaffected
		`0:4.13-3.el8_4.1< *`	unaffected
Red Hat	Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support	`0:3.6.16-5.el8_6.5< *`	unaffected
		`0:4.13-3.el8_6.2< *`	unaffected
Red Hat	Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On	`0:3.6.16-5.el8_6.5< *`	unaffected
		`0:4.13-3.el8_6.2< *`	unaffected
Red Hat	Red Hat Enterprise Linux 8.8 Telecommunications Update Service	`0:3.6.16-7.el8_8.4< *`	unaffected
		`0:4.13-4.el8_8.1< *`	unaffected
Red Hat	Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions	`0:3.6.16-7.el8_8.4< *`	unaffected
		`0:4.13-4.el8_8.1< *`	unaffected
Red Hat	Red Hat Enterprise Linux 9	`0:3.8.10-4.el9_8< *`	unaffected
		`0:3.8.10-4.el9_8< *`	unaffected
Red Hat	Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions	`0:3.7.6-21.el9_2.7< *`	unaffected
Red Hat	Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions	`0:3.8.3-4.el9_4.6< *`	unaffected
Red Hat	Red Hat Enterprise Linux 9.6 Extended Update Support	`0:3.8.3-6.el9_6.4< *`	unaffected
Red Hat	Red Hat Hardened Images	`3.8.13-1.hum1< *`	unaffected
Red Hat	Red Hat OpenShift Container Platform 4	`any`	unknown
		`any`	affected
Red Hat	Red Hat Update Infrastructure 5	`1781525684< *`	unaffected
		`1781525671< *`	unaffected
		`1781525693< *`	unaffected
		`1781525739< *`	unaffected

I. Basic Information for CVE-2026-3833

Vulnerability Information

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Vulnerability Title

Gnutls: gnutls: policy bypass due to case-sensitive nameconstraints comparison

Source: CVE Program / CVE List V5

Vulnerability Description

A flaw was found in gnutls. This vulnerability occurs because gnutls performs case-sensitive comparisons of `nameConstraints` labels, specifically for `dNSName` (DNS) or `rfc822Name` (email) constraints within `excludedSubtrees` or `permittedSubtrees`. A remote attacker can exploit this by crafting a leaf certificate with casing differences in the Subject Alternative Name (SAN), leading to a policy bypass where a certificate that should be rejected is instead accepted. This could result in unauthorized access or information disclosure.

Source: CVE Program / CVE List V5

CVSS Information

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Source: CVE Program / CVE List V5

Vulnerability Type

大小写敏感处理不恰当

Source: CVE Program / CVE List V5

Vulnerability Title

Red Hat Enterprise Linux 安全漏洞

Source: CNNVD (China National Vulnerability Database)

Vulnerability Description

Source: CNNVD (China National Vulnerability Database)

CVSS Information

N/A

Source: CNNVD (China National Vulnerability Database)

Vulnerability Type

N/A

Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor	Product	Affected Versions	CPE
-	-	0 ~ 3.8.13	-
Red Hat	Red Hat Enterprise Linux 10	0:3.8.10-4.el10_2 ~ *	`cpe:/o:redhat:enterprise_linux:10.2`
Red Hat	Red Hat Enterprise Linux 10.0 Extended Update Support	0:3.8.9-9.el10_0.19 ~ *	`cpe:/o:redhat:enterprise_linux_eus:10.0`
Red Hat	Red Hat Enterprise Linux 7 Extended Lifecycle Support	0:3.3.29-9.el7_9.2 ~ *	`cpe:/o:redhat:rhel_els:7`
Red Hat	Red Hat Enterprise Linux 8	0:3.6.16-8.el8_10.6 ~ *	`cpe:/a:redhat:enterprise_linux:8::appstream`
Red Hat	Red Hat Enterprise Linux 8	0:3.6.16-8.el8_10.6 ~ *	`cpe:/a:redhat:enterprise_linux:8::appstream`
Red Hat	Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support	0:3.6.14-10.el8_4.1 ~ *	`cpe:/a:redhat:rhel_aus:8.4::appstream`
Red Hat	Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support	0:4.13-3.el8_4.1 ~ *	`cpe:/a:redhat:rhel_aus:8.4::appstream`
Red Hat	Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On	0:3.6.14-10.el8_4.1 ~ *	`cpe:/a:redhat:rhel_aus:8.4::appstream`
Red Hat	Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On	0:4.13-3.el8_4.1 ~ *	`cpe:/a:redhat:rhel_aus:8.4::appstream`
Red Hat	Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support	0:3.6.16-5.el8_6.5 ~ *	`cpe:/a:redhat:rhel_aus:8.6::appstream`
Red Hat	Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support	0:4.13-3.el8_6.2 ~ *	`cpe:/a:redhat:rhel_aus:8.6::appstream`
Red Hat	Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On	0:3.6.16-5.el8_6.5 ~ *	`cpe:/a:redhat:rhel_aus:8.6::appstream`
Red Hat	Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On	0:4.13-3.el8_6.2 ~ *	`cpe:/a:redhat:rhel_aus:8.6::appstream`
Red Hat	Red Hat Enterprise Linux 8.8 Telecommunications Update Service	0:3.6.16-7.el8_8.4 ~ *	`cpe:/a:redhat:rhel_e4s:8.8::appstream`
Red Hat	Red Hat Enterprise Linux 8.8 Telecommunications Update Service	0:4.13-4.el8_8.1 ~ *	`cpe:/a:redhat:rhel_e4s:8.8::appstream`
Red Hat	Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions	0:3.6.16-7.el8_8.4 ~ *	`cpe:/a:redhat:rhel_e4s:8.8::appstream`
Red Hat	Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions	0:4.13-4.el8_8.1 ~ *	`cpe:/a:redhat:rhel_e4s:8.8::appstream`
Red Hat	Red Hat Enterprise Linux 9	0:3.8.10-4.el9_8 ~ *	`cpe:/a:redhat:enterprise_linux:9::appstream`
Red Hat	Red Hat Enterprise Linux 9	0:3.8.10-4.el9_8 ~ *	`cpe:/a:redhat:enterprise_linux:9::appstream`
Red Hat	Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions	0:3.7.6-21.el9_2.7 ~ *	`cpe:/a:redhat:rhel_e4s:9.2::appstream`
Red Hat	Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions	0:3.8.3-4.el9_4.6 ~ *	`cpe:/a:redhat:rhel_e4s:9.4::appstream`
Red Hat	Red Hat Enterprise Linux 9.6 Extended Update Support	0:3.8.3-6.el9_6.4 ~ *	`cpe:/a:redhat:rhel_eus:9.6::appstream`
Red Hat	Red Hat Discovery 2	1782159791 ~ *	`cpe:/a:redhat:discovery:2::el9`
Red Hat	Red Hat Discovery 2	1782166952 ~ *	`cpe:/a:redhat:discovery:2::el9`
Red Hat	Red Hat Hardened Images	3.8.13-1.hum1 ~ *	`cpe:/a:redhat:hummingbird:1`
Red Hat	Red Hat Update Infrastructure 5	1781525684 ~ *	`cpe:/a:redhat:rhui:5::el9`
Red Hat	Red Hat Update Infrastructure 5	1781525671 ~ *	`cpe:/a:redhat:rhui:5::el9`
Red Hat	Red Hat Update Infrastructure 5	1781525693 ~ *	`cpe:/a:redhat:rhui:5::el9`
Red Hat	Red Hat Update Infrastructure 5	1781525739 ~ *	`cpe:/a:redhat:rhui:5::el9`

II. Public POCs for CVE-2026-3833

#	POC Description	Source Link	Shenlong Link

AI-Generated POC Premium

No public POC found.

III. Intelligence Information for CVE-2026-3833

请登录查看更多情报信息。

Vendor Advisories for CVE-2026-3833 (12)

🔗 [Moderate] gnutls x509 nameconstraints: excluded dns/email subtree bypass via case-sensitive comparison (security report) (#1803) · Issues · gnutls / GnuTLS · GitLab Read full article
🔗 2445763 – (CVE-2026-3833) CVE-2026-3833 gnutls: GnuTLS: Policy bypass due to case-sensitive nameConstraints comparison Read full article issue-tracking x_refsource_REDHAT
🔗 RHSA-2026:20612 - Security Advisory - Portail Client Red Hat vendor-advisory x_refsource_REDHAT
🔗 RHSA-2026:26319 - Security Advisory - Red Hat Customer Portal vendor-advisory x_refsource_REDHAT
🔗 RHSA-2026:20613 - Security Advisory - Red Hat Customer Portal Read full article vendor-advisory x_refsource_REDHAT
🔗 RHSA-2026:32962 - Security Advisory - Red Hat Customer Portal Read full article vendor-advisory x_refsource_REDHAT
🔗 RHSA-2026:13274 - Security Advisory - Red Hat Customer Portal Read full article vendor-advisory x_refsource_REDHAT
🔗 RHSA-2026:33125 - Security Advisory - Red Hat Customer Portal Read full article vendor-advisory x_refsource_REDHAT
🔗 RHSA-2026:43575 - Security Advisory - Red Hat Customer Portal Read full article vendor-advisory x_refsource_REDHAT
🔗 RHSA-2026:41921 - Security Advisory - Red Hat Customer Portal Read full article vendor-advisory x_refsource_REDHAT
🔗 RHSA-2026:30849 - Security Advisory - Red Hat Customer Portal Read full article vendor-advisory x_refsource_REDHAT
🔗 RHSA-2026:30850 - Security Advisory - Red Hat Customer Portal Read full article vendor-advisory x_refsource_REDHAT

Other References for CVE-2026-3833 (5)

https://access.redhat.com/errata/RHSA-2026:26409 vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:20611 vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:58981 vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:29197 vendor-advisory x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:30004 vendor-advisory x_refsource_REDHAT

https://www.cve.org/CVERecord?id=CVE-2026-3833

IV. Related Vulnerabilities

Same weakness: CWE-178

V. Comments for CVE-2026-3833

No comments yet

Goal Reached Thanks to every supporter — we hit 100%!

CVE-2026-3833— Gnutls: gnutls: policy bypass due to case-sensitive nameconstraints comparison

Quick assessment

Possible ATT&CK Techniques 1 AI

Affected Version Matrix 33

I. Basic Information for CVE-2026-3833

Vulnerability Information

Vulnerability Title

Vulnerability Description

CVSS Information

Vulnerability Type

Vulnerability Title

Vulnerability Description

CVSS Information

Vulnerability Type

Affected Products

II. Public POCs for CVE-2026-3833

III. Intelligence Information for CVE-2026-3833

Vendor Advisories for CVE-2026-3833 (12)

Other References for CVE-2026-3833 (5)

IV. Related Vulnerabilities

V. Comments for CVE-2026-3833

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