PAPERLOCK · X.509 Name Constraints · press notes

ONE PARAGRAPH YOU CAN USE
Security researcher Oleh Konko of 1seal found that widely used TLS libraries do not always agree on how to enforce X.509 Name Constraints, the rule meant to keep a delegated certificate authority inside its allowed names. CERT/CC coordinated the disclosure and published three vulnerability notes on 13 and 14 October 2026. Some reports describe defects. Fixes have been released by pyca/cryptography (CVE-2026-34073), rustls/webpki, wolfSSL (CVE-2026-5263), AWS-LC, Go (CVE-2026-33810) and, for an independently co-reported issue, GnuTLS (CVE-2026-3833). OpenSSL has confirmed its fix in all versions it publicly supported on 2026-09-10, and a fix was merged upstream in BoringSSL. Other reports are in triage, disputed or declined, and some concern behaviour the standard does not specify. According to CERT/CC, the findings matter only where an attacker can obtain a trusted signature over chosen certificate fields, an affected validation path is reachable, and the application uses the accepted name for authorization. The notes do not report exploitation.

ACCURATE
- Libraries disagree on Name Constraints.
- Some differences are defects; some come from gaps in the standard.
- Some fixes have been released; others are merged upstream, in triage, disputed or declined.
- Exploitation requires specific conditions.

NOT ACCURATE
- HTTPS is broken.
- Browsers or phones are vulnerable.
- Library X is fixed (unless every finding for X is fixed).
- Totals made by adding records across notes.
- Hackers are exploiting this.

HOW TO COUNT THIS
3       CERT/CC notes
        Unit: CERT/CC vulnerability note
        Counting rule: Notes VU#573195, VU#948176 and VU#410595, as published.
        Excluded: Nothing else is counted as a note.
        Count as of: 2026-10-13 / 2026-10-14 (publication of the notes)
        Basis on the site: https://paperlock.org/method/#fact-N1
        Sources: CERT/CC VU#573195 (https://kb.cert.org/vuls/id/573195); CERT/CC VU#948176 (https://kb.cert.org/vuls/id/948176); CERT/CC VU#410595 (https://kb.cert.org/vuls/id/410595)

12      Libraries named in the notes — the list is next to the findings table (https://paperlock.org/findings/#findings)
        Unit: library named in a note
        Counting rule: Distinct libraries named across the three notes.
        Excluded: rustls/webpki appears only in references and is not counted here (it is listed in the findings table).
        Count as of: 2026-10-13 / 2026-10-14 (publication of the notes)
        Basis on the site: https://paperlock.org/method/#fact-N2
        Sources: CERT/CC VU#573195 (https://kb.cert.org/vuls/id/573195); CERT/CC VU#948176 (https://kb.cert.org/vuls/id/948176); CERT/CC VU#410595 (https://kb.cert.org/vuls/id/410595)

6       CVEs with published credit to 1seal: CVE-2026-3833, CVE-2026-34073, CVE-2026-5263, CVE-2026-93600, CVE-2026-93601, CVE-2026-33810. CVE-2026-27137 (Go) fixes a matching mechanism but credits another researcher and is not counted.
        Unit: CVE ID with published credit to Oleh Konko / 1seal
        Counting rule: Unique CVE IDs. A CVE counts once even when several finding rows cite it. Advisories (GHSA) are not CVEs and are not counted here.
        Excluded: CVE-2026-27137 (Go): fixes a matching mechanism but credits another researcher.
        Count as of: 2026-10-14; record dates differ by row, see the findings table
        Basis on the site: https://paperlock.org/method/#fact-N3
        Sources: CVE-2026-3833 (https://www.cve.org/CVERecord?id=CVE-2026-3833); CVE-2026-34073 (https://www.cve.org/CVERecord?id=CVE-2026-34073); CVE-2026-5263 (https://www.cve.org/CVERecord?id=CVE-2026-5263); CVE-2026-93600 (https://www.cve.org/CVERecord?id=CVE-2026-93600); CVE-2026-93601 (https://www.cve.org/CVERecord?id=CVE-2026-93601); CVE-2026-33810 (https://www.cve.org/CVERecord?id=CVE-2026-33810)

2       GHSA advisories for AWS-LC (the rustls/webpki advisories are counted through their CVEs above)
        Unit: GHSA advisory (unique ID)
        Counting rule: Unique GHSA IDs cited for AWS-LC. The same two advisories appear on two finding rows and are counted once each.
        Excluded: The 6 credited CVEs (N3) are a different unit and are not added to this count. The rustls/webpki advisories are counted through their CVEs in N3.
        Record date: 2026-03-19 (as of both AWS-LC rows)
        Count as of: 2026-10-14
        Basis on the site: https://paperlock.org/method/#fact-N6
        Sources: GHSA-3jrg-j22w-mpmc (https://github.com/aws/aws-lc/security/advisories/GHSA-3jrg-j22w-mpmc); GHSA-394x-vwmw-crm3 (https://github.com/aws/aws-lc-rs/security/advisories/GHSA-394x-vwmw-crm3)

13 / 5  Records in VU#948176 / VU#410595. Records are not confirmed vulnerabilities, and their statuses differ.
        Unit: record inside a CERT/CC note
        Counting rule: 13 records in VU#948176 and 5 in VU#410595. A record is not a confirmed vulnerability and record statuses differ. The two figures are not summed.
        Excluded: Records are not CVEs, GHSAs or findings and are not added to them.
        Count as of: 2026-10-13 / 2026-10-14 (publication of the notes)
        Basis on the site: https://paperlock.org/method/#fact-N4
        Sources: CERT/CC VU#948176 (https://kb.cert.org/vuls/id/948176); CERT/CC VU#410595 (https://kb.cert.org/vuls/id/410595)

Do not add these numbers together.

Quotes: none at launch. Interviews: labs@1seal.org.
Mark licence: CC BY 4.0, 1seal. The canonical records are the CERT/CC notes; please link them.

Site: https://paperlock.org/   Findings table: https://paperlock.org/findings/#findings