CVE-2026-82617

The two built-in name-finder patterns exposed by opennlp.tools.namefind.RegexNameFinderFactory - DEFAULT_REGEX_NAME_FINDER.EMAIL and DEFAULT_REGEX_NAME_FINDER.URL - contain ambiguous nested quantifiers. An application that obtains these finders through RegexNameFinderFactory.getDefaultRegexNameFinders(...) and then applies them to untrusted text through RegexNameFinder.find(String[]) or RegexNameFinder.find(String) can be driven into super-linear backtracking or into unbounded matcher recursion by a small crafted input.

For the EMAIL pattern, a long run of local-part characters that is never followed by an @ forces the matcher to re-scan to end-of-input from every starting offset. Cost grows quadratically with input length: an input of approximately 32 KB consumes several seconds of CPU in a single find() call and returns no match, and each doubling of the input multiplies the cost roughly four-fold.

For the URL pattern, the query-string sub-expression nests a capturing repetition inside an outer repetition. The JDK matcher recurses once per query token, so an input of approximately 4 KB containing many &-separated tokens exhausts the thread stack and causes java.lang.StackOverflowError to propagate out of find(), terminating the calling thread. On a thread created with a smaller stack (for example -Xss512k, typical of server worker pools) approximately 1 KB is sufficient.

In both cases an attacker who can supply text for analysis can convert a single request into seconds to minutes of pinned CPU, or into an abrupt thread death, denying service to the embedding application. No authentication, special configuration, or model file is required beyond the application having selected one of the two built-in finders.

This issue affects Apache OpenNLP: from 2.0.0 through 2.5.11; from 3.0.0-M1 through 3.0.0-M5.

Users are recommended to upgrade to version 2.5.12, or to 3.0.0-M6 for users tracking the 3.0.0 milestone line, which fix the issue.

Database specific

{
    "cna_assigner": "apache",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82617.json",
    "unresolved_ranges": [
        {
            "extracted_events": [
                {
                    "introduced": "3.0.0-M1"
                },
                {
                    "fixed": "3.0.0-M6"
                },
                {
                    "introduced": "2.0.0"
                },
                {
                    "fixed": "2.5.12"
                }
            ],
            "source": "AFFECTED_FIELD"
        },
        {
            "extracted_events": [
                {
                    "fixed": "RegexNameFinderFactory.getDefaultRegexNameFinders"
                },
                {
                    "fixed": "RegexNameFinder.find"
                },
                {
                    "introduced": "2.0.0"
                },
                {
                    "fixed": "2.5.11"
                },
                {
                    "introduced": "3.0.0-M1"
                },
                {
                    "fixed": "3.0.0-M5"
                }
            ],
            "source": "DESCRIPTION"
        }
    ]
}

References

Affected packages

Git / github.com/apache/opennlp

Affected ranges

Type

GIT

Repo

https://github.com/apache/opennlp

Events

Introduced

804ad5579b829f3a9b7b2bf3af819c53d6bb4290

Fixed

e27ddb38bed9406a045a0fc9bdf9378422b398a6

Introduced

1e9f4d89af6ebc5b6860087589146817dff08b44

Last Affected

936db0e9b79c9150afcf2c06e107b2b958ab536d

Database specific

Show details

{
    "cpe": [
        "cpe:2.3:a:apache:opennlp:*:*:*:*:*:*:*:*",
        "cpe:2.3:a:apache:opennlp:3.0.0:m1:*:*:*:*:*:*",
        "cpe:2.3:a:apache:opennlp:3.0.0:m2:*:*:*:*:*:*",
        "cpe:2.3:a:apache:opennlp:3.0.0:m3:*:*:*:*:*:*",
        "cpe:2.3:a:apache:opennlp:3.0.0:m4:*:*:*:*:*:*",
        "cpe:2.3:a:apache:opennlp:3.0.0:m5:*:*:*:*:*:*"
    ],
    "extracted_events": [
        {
            "introduced": "2.0.0"
        },
        {
            "fixed": "2.5.12"
        },
        {
            "introduced": "3.0.0-m1"
        },
        {
            "last_affected": "3.0.0-m1"
        },
        {
            "introduced": "3.0.0-m2"
        },
        {
            "last_affected": "3.0.0-m2"
        },
        {
            "introduced": "3.0.0-m3"
        },
        {
            "last_affected": "3.0.0-m3"
        },
        {
            "introduced": "3.0.0-m4"
        },
        {
            "last_affected": "3.0.0-m4"
        },
        {
            "introduced": "3.0.0-m5"
        },
        {
            "last_affected": "3.0.0-m5"
        }
    ],
    "source": [
        "CPE_RANGE",
        "CPE_STRING"
    ]
}

Affected versions

3.*

3.0.0-m1

3.0.0-m2

3.0.0-m3

3.0.0-m4

3.0.0-m5

opennlp-2.*

opennlp-2.0.0

opennlp-2.1.0

opennlp-2.1.1

opennlp-2.2.0

opennlp-2.3.0

opennlp-2.3.2

opennlp-3.*

opennlp-3.0.0-M5

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-82617.json"