diff --git a/src/univers/version_range.py b/src/univers/version_range.py
index 8db5253e..996bd4c7 100644
--- a/src/univers/version_range.py
+++ b/src/univers/version_range.py
@@ -4,6 +4,7 @@
 #
 # Visit https://aboutcode.org and https://github.com/aboutcode-org/univers for support and download.
 
+import re
 from typing import List
 from typing import Union
 
@@ -772,6 +773,71 @@ def from_native(cls, string):
 
         return cls(constraints=constraints)
 
+    @classmethod
+    def from_ossa_native(cls, string):
+        """
+        Returns a PypiVersionRange built from an OpenStack Security Advisory (OSSA) version constraint ``string``.
+
+        See: https://github.com/openstack/ossa
+
+        For example::
+
+        >>> str(PypiVersionRange.from_ossa_native("<=5.0.3, >=6.0.0 <=6.1.0 and ==7.0.0"))
+        'vers:pypi/<=5.0.3|>=6.0.0|<=6.1.0|7.0.0'
+
+        >>> str(PypiVersionRange.from_ossa_native("<=14.0.10, >=15.0.0 <=15.0.8, >=16.0.0 <=16.0.3"))
+        'vers:pypi/<=14.0.10|>=15.0.0|<=15.0.8|>=16.0.0|<=16.0.3'
+
+        >>> str(PypiVersionRange.from_ossa_native("<20.2.1, >=21.0.0 <21.2.1, ==22.0.0"))
+        'vers:pypi/<20.2.1|>=21.0.0|<21.2.1|22.0.0'
+        """
+
+        # Normalize "and" keyword to comma
+        # "<=5.0.3, >=6.0.0 <=6.1.0 and ==7.0.0" -> "<=5.0.3, >=6.0.0 <=6.1.0, ==7.0.0"
+        string = string.replace(" and ", ",")
+
+        # Remove spaces around operators
+        # "<=5.0.3, >=6.0.0 <=6.1.0, ==7.0.0" -> "<=5.0.3,>=6.0.0<=6.1.0,==7.0.0"
+        string = re.sub(r"\s+([<>=!]+)", r"\1", string)
+        string = re.sub(r"([<>=!]+)\s+", r"\1", string)
+
+        # Insert comma between consecutive constraints
+        # "<=5.0.3,>=6.0.0<=6.1.0,==7.0.0" -> "<=5.0.3,>=6.0.0,<=6.1.0,==7.0.0"
+        string = re.sub(r"(\d)([<>=!])", r"\1,\2", string)
+
+        constraints = []
+        for part in string.split(","):
+
+            # Default to exact match for bare version numbers
+            # "1.16.0" -> "=1.16.0"
+            comparator = "="
+            version = part
+
+            for op, vers_op in cls.vers_by_native_comparators.items():
+                if part.startswith(op):
+                    comparator = vers_op
+                    version = part[len(op) :]
+                    break
+
+            # Handle bare "=" for exact match
+            # "=18.0.0" -> "18.0.0"
+            if version.startswith("="):
+                version = version[1:]
+
+            try:
+                constraints.append(
+                    VersionConstraint(
+                        comparator=comparator,
+                        version=cls.version_class(version),
+                    )
+                )
+            except (ValueError, TypeError) as e:
+                raise InvalidVersionRange(
+                    f"Invalid version constraint {part!r} in OSSA version string {string!r}: {e}"
+                ) from e
+
+        return cls(constraints=constraints)
+
 
 class MavenVersionRange(VersionRange):
     """
diff --git a/tests/test_version_range.py b/tests/test_version_range.py
index ed3f8a28..a38a0935 100644
--- a/tests/test_version_range.py
+++ b/tests/test_version_range.py
@@ -255,6 +255,48 @@ def test_PypiVersionRange_raises_ivr_for_unsupported_and_invalid_ranges(range, w
         assert expected == str(PypiVersionRange.from_native(range))
 
 
+@pytest.mark.parametrize(
+    "string, expected",
+    [
+        (  # OSSA-2016-013
+            "<=5.0.3, >=6.0.0 <=6.1.0 and ==7.0.0",
+            "vers:pypi/<=5.0.3|>=6.0.0|<=6.1.0|7.0.0",
+        ),
+        (  # OSSA-2017-005
+            "<=14.0.10, >=15.0.0 <=15.0.8, >=16.0.0 <=16.0.3",
+            "vers:pypi/<=14.0.10|>=15.0.0|<=15.0.8|>=16.0.0|<=16.0.3",
+        ),
+        (  # OSSA-2019-003
+            "<17.0.12, >=18.0.0 <18.2.2, >=19.0.0 <19.0.2",
+            "vers:pypi/<17.0.12|>=18.0.0|<18.2.2|>=19.0.0|<19.0.2",
+        ),
+        (  # OSSA-2020-006
+            "<19.3.1, >=20.0.0 <20.3.1, ==21.0.0",
+            "vers:pypi/<19.3.1|>=20.0.0|<20.3.1|21.0.0",
+        ),
+        (  # OSSA-2026-001
+            ">=10.5.0 <10.7.2, >=10.8.0 <10.9.1, >=10.10.0 <10.12.1",
+            "vers:pypi/>=10.5.0|<10.7.2|>=10.8.0|<10.9.1|>=10.10.0|<10.12.1",
+        ),
+        (  # OSSA-2021-001
+            "<16.3.3, >=17.0.0 <17.1.3, =18.0.0",
+            "vers:pypi/<16.3.3|>=17.0.0|<17.1.3|18.0.0",
+        ),
+        (  # empty string should raise InvalidVersionRange
+            "",
+            "InvalidVersionRange",
+        ),
+    ],
+)
+def test_PypiVersionRange_from_ossa_native(string, expected):
+    if expected == "InvalidVersionRange":
+        with pytest.raises(InvalidVersionRange):
+            PypiVersionRange.from_ossa_native(string)
+    else:
+        result = PypiVersionRange.from_ossa_native(string)
+        assert expected == str(result)
+
+
 def test_invert():
     vers_with_equal_operator = VersionRange.from_string("vers:gem/1.0")
     assert str(vers_with_equal_operator.invert()) == "vers:gem/!=1.0"