Vulnerability-Lookup

ALSA-2026:84590

Vulnerability from osv_almalinux – Published: 2026-10-19 00:00 – Updated: 2026-10-19 09:23 – Source website

Summary

Moderate: perl-URI security update

Details

This module implements the URI class. Objects of this class represent "Uniform Resource Identifier references" as specified in RFC 2396 (and updated by RFC 2732).

Security Fix(es):

URI: URI (for Perl): Security bypass due to incorrect hostname encoding via missing Unicode normalization (CVE-2026-19953)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

References

URL

Type

	https://access.redhat.com/errata/RHSA-2026:84590	ADVISORY
	https://access.redhat.com/security/cve/CVE-2026-19953	REPORT
	https://bugzilla.redhat.com/2526492	REPORT
	https://errata.almalinux.org/8/ALSA-2026-84590.html	ADVISORY

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "AlmaLinux:8",
        "name": "perl-URI"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.73-4.el8_10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "This module implements the URI class. Objects of this class represent \"Uniform Resource Identifier references\" as specified in RFC 2396 (and updated by RFC 2732).  \n\nSecurity Fix(es):  \n\n  * URI: URI (for Perl): Security bypass due to incorrect hostname encoding via missing Unicode normalization (CVE-2026-19953)\n\n\nFor more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.\n",
  "id": "ALSA-2026:84590",
  "modified": "2026-10-19T09:23:44Z",
  "published": "2026-10-19T00:00:00Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:84590"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2026-19953"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/2526492"
    },
    {
      "type": "ADVISORY",
      "url": "https://errata.almalinux.org/8/ALSA-2026-84590.html"
    }
  ],
  "related": [
    "CVE-2026-19953"
  ],
  "summary": "Moderate: perl-URI security update"
}

CVE-2026-19953 (GCVE-0-2026-19953)

Vulnerability from cvelistv5 – Published: 2026-08-31 17:29 – Updated: 2026-09-01 15:16

Title

URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep

Summary

URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep. nameprep lowercases each host label but performs no Unicode normalization. IDNA requires a label to be normalized to Form C before it is encoded (RFC 5891), so a label that is not already in NFC is encoded to a different A-label than its normalized form. A label built from the precomposed Devanagari sequence U+0958 U+093E encodes to xn--72b5c without normalization but to xn--11b2fg after NFC normalization, and xn--72b5c does not round-trip back to the original label. Any caller that reads host() from a URI built from untrusted input and uses it for a security decision (an allow or deny list, an SSRF filter, deduplication, a cache key) sees the non-standard label, while a client that fetches the same URL resolves the NFC form, so the check and the fetch can disagree about the host.

Severity

6.5 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-01 15:16 UTC

CWE

CWE-1289 - Improper Validation of Unsafe Equivalence in Input

Assigner

CPANSec CNA under the redhat root

CNA scorecard C 63/100 over 296 records in the last 180 days details

References

5 references

URL	Tags
https://github.com/libwww-perl/URI/commit/956619a…	patch
https://github.com/libwww-perl/URI/pull/191	issue-tracking
https://metacpan.org/release/OALDERS/URI-5.36/changes	release-notes
https://www.rfc-editor.org/rfc/rfc5891#section-5.2	technical-description
http://www.openwall.com/lists/oss-security/2026/0…

Impacted products

1 product

Vendor	Product	Version
		Affected: 0 , < 5.36 (custom)

Credits

Naseeb Dangi (naseeb0), Nankai University

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2026-08-31T20:07:50.422Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "http://www.openwall.com/lists/oss-security/2026/08/31/14"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "NONE",
              "baseScore": 6.5,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "LOW",
              "integrityImpact": "LOW",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2026-19953",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-01T15:16:46.820304Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-01T15:16:50.672Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://cpan.org/modules",
          "defaultStatus": "unaffected",
          "modules": [
            "URI"
          ],
          "packageName": "URI",
          "packageURL": "pkg:cpan/URI",
          "programFiles": [
            "lib/URI/_idna.pm"
          ],
          "programRoutines": [
            {
              "name": "URI::_idna::nameprep"
            }
          ],
          "repo": "https://github.com/libwww-perl/URI",
          "versions": [
            {
              "lessThan": "5.36",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Naseeb Dangi (naseeb0), Nankai University"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep.\n\nnameprep lowercases each host label but performs no Unicode normalization. IDNA requires a label to be normalized to Form C before it is encoded (RFC 5891), so a label that is not already in NFC is encoded to a different A-label than its normalized form. A label built from the precomposed Devanagari sequence U+0958 U+093E encodes to xn--72b5c without normalization but to xn--11b2fg after NFC normalization, and xn--72b5c does not round-trip back to the original label.\n\nAny caller that reads host() from a URI built from untrusted input and uses it for a security decision (an allow or deny list, an SSRF filter, deduplication, a cache key) sees the non-standard label, while a client that fetches the same URL resolves the NFC form, so the check and the fetch can disagree about the host."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-1289",
              "description": "CWE-1289 Improper Validation of Unsafe Equivalence in Input",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-31T17:29:42.929Z",
        "orgId": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
        "shortName": "CPANSec"
      },
      "references": [
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/libwww-perl/URI/commit/956619a9e94f86d8d2c529b4e06a3674c54a73e7.patch"
        },
        {
          "tags": [
            "issue-tracking"
          ],
          "url": "https://github.com/libwww-perl/URI/pull/191"
        },
        {
          "tags": [
            "release-notes"
          ],
          "url": "https://metacpan.org/release/OALDERS/URI-5.36/changes"
        },
        {
          "tags": [
            "technical-description"
          ],
          "url": "https://www.rfc-editor.org/rfc/rfc5891#section-5.2"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Upgrade to URI 5.36 or later."
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep",
      "x_generator": {
        "engine": "cpansec-cna-tool 0.1"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
    "assignerShortName": "CPANSec",
    "cveId": "CVE-2026-19953",
    "datePublished": "2026-08-31T17:29:42.929Z",
    "dateReserved": "2026-08-15T21:13:08.480Z",
    "dateUpdated": "2026-09-01T15:16:50.672Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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