Tie::Hash::Regex versions before 2.0.0 for Perl will throw an exception on unparseable lookup keys. The FETCH, EXISTS and DELETE methods throw an exception when on malformed regular expressions. Each method falls back to a regex match when the key is not already stored in the hash, compiling the caller's key with a bare qr// and no eval guard.
A key that is not a valid regular expression pattern, such as a single unmatched bracket, dies. An application that looks up externally supplied strings in a tied hash will die on an invalid key.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Weakness Type (CWE)
References 3
https://github.com/davorg-cpan/tie-hash-regex/commit/4239732cb76233543e2ded8ff5…
9b29abf9-4ab0-4765-b253-1875cd9b441e
https://metacpan.org/release/DAVECROSS/Tie-Hash-Regex-2.0.0/source/Changes
9b29abf9-4ab0-4765-b253-1875cd9b441e
http://www.openwall.com/lists/oss-security/2026/08/22/2
af854a3a-2127-422b-91ae-364da2661108