diff --git a/CHANGELOG.md b/CHANGELOG.md
index 845d78a1..d5098f3e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,12 @@ All versions prior to 0.0.9 are untracked.
 
 ## [Unreleased]
 
+### Fixed
+
+* CLI: the `--format=markdown` and `--format=columns` output formats are no
+  longer broken by long vulnerability descriptions from the OSV and PyPI
+  vulnerability sources ([#323](https://github.com/trailofbits/pip-audit/pull/323))
+
 ## [2.4.1]
 
 ### Fixed
diff --git a/pip_audit/_service/osv.py b/pip_audit/_service/osv.py
index c9740401..5e5dfe14 100644
--- a/pip_audit/_service/osv.py
+++ b/pip_audit/_service/osv.py
@@ -98,6 +98,12 @@ def query(self, spec: Dependency) -> Tuple[Dependency, List[VulnerabilityResult]
             if description is None:
                 description = "N/A"
 
+            # The "summary" field should be a single line, but "details" might
+            # be multiple (Markdown-formatted) lines. So, we normalize our
+            # description into a single line (and potentially break the Markdown
+            # formatting in the process).
+            description = description.replace("\n", " ")
+
             aliases = set(vuln.get("aliases", []))
 
             # OSV doesn't mandate this field either. There's very little we
diff --git a/pip_audit/_service/pypi.py b/pip_audit/_service/pypi.py
index 87edeb0b..b12fab20 100644
--- a/pip_audit/_service/pypi.py
+++ b/pip_audit/_service/pypi.py
@@ -117,8 +117,21 @@ def query(self, spec: Dependency) -> Tuple[Dependency, List[VulnerabilityResult]
             # The ranges aren't guaranteed to come in chronological order
             fix_versions.sort()
 
+            description = v.get("summary")
+            if description is None:
+                description = v.get("details")
+
+            if description is None:
+                description = "N/A"
+
+            # The "summary" field should be a single line, but "details" might
+            # be multiple (Markdown-formatted) lines. So, we normalize our
+            # description into a single line (and potentially break the Markdown
+            # formatting in the process).
+            description = description.replace("\n", " ")
+
             results.append(
-                VulnerabilityResult(v["id"], v["details"], fix_versions, set(v["aliases"]))
+                VulnerabilityResult(v["id"], description, fix_versions, set(v["aliases"]))
             )
 
         return spec, results
diff --git a/test/service/test_osv.py b/test/service/test_osv.py
index 752bddfe..bf8c03ba 100644
--- a/test/service/test_osv.py
+++ b/test/service/test_osv.py
@@ -171,7 +171,9 @@ def test_osv_unsupported_schema_version(monkeypatch, version):
     ["summary", "details", "description"],
     [
         ("fakesummary", "fakedetails", "fakesummary"),
+        ("fakesummary\nanother line", "fakedetails", "fakesummary another line"),
         (None, "fakedetails", "fakedetails"),
+        (None, "fakedetails\nanother line", "fakedetails another line"),
         (None, None, "N/A"),
     ],
 )
diff --git a/test/service/test_pypi.py b/test/service/test_pypi.py
index 4eca9c17..3b1f1e00 100644
--- a/test/service/test_pypi.py
+++ b/test/service/test_pypi.py
@@ -144,7 +144,7 @@ def json(self):
                         {
                             "aliases": ["foo", "bar"],
                             "id": "VULN-0",
-                            "details": "The first vulnerability",
+                            "summary": "The first vulnerability",
                             "fixed_in": ["1.1", "1.4"],
                         }
                     ]
@@ -172,6 +172,57 @@ def json(self):
     )
 
 
+@pytest.mark.parametrize(
+    ["summary", "details", "description"],
+    [
+        ("fakesummary", "fakedetails", "fakesummary"),
+        ("fakesummary\nanother line", "fakedetails", "fakesummary another line"),
+        (None, "fakedetails", "fakedetails"),
+        (None, "fakedetails\nanother line", "fakedetails another line"),
+        (None, None, "N/A"),
+    ],
+)
+def test_pypi_vuln_description_fallbacks(monkeypatch, cache_dir, summary, details, description):
+    def get_mock_response():
+        class MockResponse:
+            def raise_for_status(self):
+                pass
+
+            def json(self):
+                return {
+                    "vulnerabilities": [
+                        {
+                            "aliases": ["foo", "bar"],
+                            "id": "VULN-0",
+                            "summary": summary,
+                            "details": details,
+                            "fixed_in": ["1.1", "1.4"],
+                        }
+                    ]
+                }
+
+        return MockResponse()
+
+    monkeypatch.setattr(
+        service.pypi, "caching_session", lambda _: get_mock_session(get_mock_response)
+    )
+
+    pypi = service.PyPIService(cache_dir)
+    dep = service.ResolvedDependency("foo", Version("1.0"))
+    results: Dict[service.Dependency, List[service.VulnerabilityResult]] = dict(
+        pypi.query_all(iter([dep]))
+    )
+    assert len(results) == 1
+    assert dep in results
+    assert len(results[dep]) == 1
+    assert results[dep][0] == service.VulnerabilityResult(
+        id="VULN-0",
+        description=description,
+        fix_versions=[Version("1.1"), Version("1.4")],
+        aliases={"foo", "bar"},
+    )
+
+
 def test_pypi_no_vuln_key(monkeypatch, cache_dir):
     def get_mock_response():
         class MockResponse:
@@ -209,7 +260,7 @@ def json(self):
                         {
                             "aliases": ["foo", "bar"],
                             "id": "VULN-0",
-                            "details": "The first vulnerability",
+                            "summary": "The first vulnerability",
                             "fixed_in": ["invalid_version"],
                         }
                     ]
@@ -278,7 +329,7 @@ def json(self):
                     "vulnerabilities": [
                         {
                             "id": "VULN-0",
-                            "details": "The first vulnerability",
+                            "summary": "The first vulnerability",
                             "fixed_in": ["1.1"],
                         }
                     ],