GHSA-2XF4-CG6J-VHGQ symfony/polyfill-intl-idn: xn-- labels with ASCII-only Punycode payloads are treated as equivalent to their decoded form

Description symfony/polyfill-intl-idn provides a userland implementation of idntoutf8 and idntoascii for runtimes that lack the intl extension. Its Idn::process method decodes labels prefixed with xn-- using Punycode but never enforces the validity criterion added in UTS 46 revision 33 Section 4...

DEBIAN-CVE-2026-39821

The ToASCII and ToUnicode functions incorrectly accept Punycode-encoded labels that decode to an ASCII-only label. For example, ToUnicode"xn--example-.com" incorrectly returns the name "example.com" rather than an error. This behavior can lead to privilege escalation in programs using the idna...

UBUNTU-CVE-2026-39821

The ToASCII and ToUnicode functions incorrectly accept Punycode-encoded labels that decode to an ASCII-only label. For example, ToUnicode"xn--example-.com" incorrectly returns the name "example.com" rather than an error. This behavior can lead to privilege escalation in programs using the idna...

CVE-2026-39821

The ToASCII and ToUnicode functions incorrectly accept Punycode-encoded labels that decode to an ASCII-only label. For example, ToUnicode"xn--example-.com" incorrectly returns the name "example.com" rather than an error. This behavior can lead to privilege escalation in programs using the idna...

EUVD-2026-31449

The ToASCII and ToUnicode functions incorrectly accept Punycode-encoded labels that decode to an ASCII-only label. For example, ToUnicode"xn--example-.com" incorrectly returns the name "example.com" rather than an error. This behavior can lead to privilege escalation in programs using the idna...

GHSA-H97M-WW89-6JMQ `idna` accepts Punycode labels that do not produce any non-ASCII when decoded

idna 0.5.0 and earlier accepts Punycode labels that do not produce any non-ASCII output, which means that either ASCII labels or the empty root label can be masked such that they appear unequal without IDNA processing or when processed with a different implementation and equal when processed with...