DEBIAN-CVE-2026-42789

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Source
https://security-tracker.debian.org/tracker/CVE-2026-42789
Import Source
https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-42789.json
JSON Data
https://api.test.osv.dev/v1/vulns/DEBIAN-CVE-2026-42789
Upstream
Published
2026-05-27T14:16:53Z
Modified
2026-09-19T23:00:14Z
Severity
  • 4.8 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N CVSS Calculator
Summary
[none]
Details

Improper Following of a Certificate's Chain of Trust vulnerability in Erlang OTP public_key (pubkey_cert module) allows a non-CA certificate to be accepted as an intermediate issuer, enabling certificate chain forgery. In lib/public_key/src/pubkey_cert.erl, pubkey_cert:validate_extensions/7 contains two flaws that together allow a certificate with basicConstraints cA:false and no keyUsage extension to be used as an intermediate issuer in a chain passed to public_key:pkix_path_validation/3: the cA:false clause recurses into the remaining extensions without rejecting the certificate when it is in issuer position, and the keyUsage check only fires when the extension is present, so a certificate lacking keyUsage entirely bypasses the keyCertSign enforcement. Any party holding an end-entity certificate with basicConstraints cA:false and no keyUsage extension, issued by any CA in the victim's trust store, can use that certificate's private key to sign forged leaf certificates for arbitrary identities. public_key:pkix_path_validation/3 accepts the resulting chain, and by extension every TLS or mTLS endpoint built on the OTP ssl application that relies on the default verifier is affected, including server identity verification on the client side and client certificate verification on mTLS servers. This issue affects OTP from OTP 17.0 before OTP 29.0.1, OTP 28.5.0.1, OTP 27.3.4.12 and OTP 26.2.5.21, corresponding to public_key from 0.22 before 1.21.1, 1.20.3.1, 1.17.1.3 and 1.15.1.7.

References

Affected packages

Debian:12 / erlang

Package

Name
erlang
Purl
pkg:deb/debian/erlang?arch=source&distro=bookworm

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1:25.*
1:25.2.3+dfsg-1
1:25.2.3+dfsg-1+deb12u1
1:25.2.3+dfsg-1+deb12u2
1:25.2.3+dfsg-1+deb12u3
1:25.2.3+dfsg-1+deb12u4
1:25.3.2.8+dfsg-1
1:25.3.2.10+dfsg-1
1:25.3.2.10+dfsg-2
1:25.3.2.11+dfsg-1
1:25.3.2.12+dfsg-1
1:25.3.2.12+dfsg-2
1:25.3.2.12+dfsg-3
1:26.*
1:26.0~rc2+dfsg-1
1:26.0~rc3+dfsg-1
1:26.0+dfsg-1
1:26.0.1+dfsg-1
1:26.0.2+dfsg-1
1:26.1.2+dfsg-1
1:26.2.1+dfsg-1
1:26.2.4+dfsg-1
1:27.*
1:27.0~rc3+dfsg-1
1:27.0~rc3+dfsg-2
1:27.0~rc3+dfsg-3
1:27.0~rc3+dfsg-4
1:27.0+dfsg-1
1:27.0.1+dfsg-1
1:27.0.1+dfsg-2
1:27.0.1+dfsg-3
1:27.1.2+dfsg-1
1:27.2+dfsg-1
1:27.2+dfsg-2
1:27.2+dfsg-3~exp1
1:27.2.1+dfsg-1
1:27.2.1+dfsg-2
1:27.2.2+dfsg-1
1:27.2.3+dfsg-1
1:27.2.4+dfsg-1
1:27.3+dfsg-1
1:27.3.1+dfsg-1
1:27.3.2+dfsg-1
1:27.3.3+dfsg-1
1:27.3.4+dfsg-1
1:27.3.4.1+dfsg-1
1:27.3.4.3+dfsg-1
1:27.3.4.4+dfsg-1
1:27.3.4.6+dfsg-1
1:27.3.4.8+dfsg-1
1:27.3.4.9+dfsg-1
1:27.3.4.10+dfsg-1
1:27.3.4.11+dfsg-1
1:27.3.4.11+dfsg-2
1:27.3.4.11+dfsg-3
1:27.3.4.11+dfsg-4
1:27.3.4.11+dfsg-5
1:27.3.4.11+dfsg-6
1:27.3.4.11+dfsg-7
1:27.3.4.12+dfsg-1
1:28.*
1:28.0+dfsg-1
1:28.0.1+dfsg-1
1:28.0.2+dfsg-1
1:28.0.4+dfsg-1
1:28.1.1+dfsg-1
1:28.2+dfsg-1
1:28.3+dfsg-1
1:28.3.1+dfsg-1
1:29.*
1:29.0~rc1+dfsg-1
1:29.0~rc1+dfsg-2
1:29.0~rc2+dfsg-1
1:29.0~rc3+dfsg-1
1:29.0~rc3+dfsg-2
1:29.0~rc3+dfsg-3
1:29.0~rc3+dfsg-4
1:29.0+dfsg-1
1:29.0+dfsg-2
1:29.0.1+dfsg-1
1:29.0.2+dfsg-1
1:29.0.3+dfsg-1
1:29.0.4+dfsg-1
1:29.0.6+dfsg-1

Ecosystem specific 

{
    "urgency":  "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-42789.json"

Debian:13 / erlang

Package

Name
erlang
Purl
pkg:deb/debian/erlang?arch=source&distro=trixie

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1:27.3.4.1+dfsg-1+deb13u3

Affected versions

1:27.*
1:27.3.4.1+dfsg-1
1:27.3.4.1+dfsg-1+deb13u1
1:27.3.4.1+dfsg-1+deb13u2

Ecosystem specific 

{
    "urgency":  "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-42789.json"

Debian:14 / erlang

Package

Name
erlang
Purl
pkg:deb/debian/erlang?arch=source&distro=forky

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
1:27.3.4.12+dfsg-1

Affected versions

1:27.*
1:27.3.4.1+dfsg-1
1:27.3.4.3+dfsg-1
1:27.3.4.4+dfsg-1
1:27.3.4.6+dfsg-1
1:27.3.4.8+dfsg-1
1:27.3.4.9+dfsg-1
1:27.3.4.10+dfsg-1
1:27.3.4.11+dfsg-1
1:27.3.4.11+dfsg-2
1:27.3.4.11+dfsg-3
1:27.3.4.11+dfsg-4
1:27.3.4.11+dfsg-5
1:27.3.4.11+dfsg-6
1:27.3.4.11+dfsg-7

Ecosystem specific 

{
    "urgency":  "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-42789.json"