PowSyBl Core Contains a Polynomial ReDoS in RegexCriterion

Impact

What kind of vulnerability is it? Who is impacted?

This is an advisory for a potential polynomial Regular Expression Denial of Service (ReDoS) vulnerability in the RegexCriterion class. This class compiles and evaluates an unvalidated, user-supplied regular expression against the identifier of an Identifiable object via Pattern.compile(regex).matcher(id).find().

To trigger polynomial ReDoS in RegexCriterion, two attacker-controlled conditions must be met:

• Control over the regex input passed into the constructor:
  • Example: An attacker supplies a malicious pattern such as (.*a){10000}.
• Control or influence over the output of Identifiable.getId():
  • Example: A long string like "aaaa...!" that forces excessive backtracking.

If both conditions are satisfied, a malicious actor can cause significant CPU exhaustion through repeated or recursive filter(...) calls — especially if performed over large network models or filtering operations. While this class does not handle file or memory data directly, its reliance on untrusted regular expressions and potentially attacker-controlled identifiers makes it vulnerable to polynomial ReDoS under the right conditions. This risk is amplified when the library is used in dynamic or scriptable environments where external users control either criterion construction or network object identifiers. Although not as dangerous as catastrophic exponential ReDoS, the polynomial pattern still induces significant performance degradation as input size increases.

Am I impacted?

Since RegexCriterion are used to define contingencies or limit reductions, you are vulnerable if:

• you allow untrusted users to define contingency lists or limit reductions using this criterion;
• OR you load untrusted contingencies or limit reductions files

AND use them with a network containing untrusted identifiers.

Patches

com.powsybl:powsybl-iidm-criteria:6.7.2 and higher

References

powsybl-core v6.7.2