diff --git a/docs/development.md b/docs/development.md
index 566c9872..10a53bf6 100644
--- a/docs/development.md
+++ b/docs/development.md
@@ -100,6 +100,15 @@ version is pinned so relocking always produces the same output:
   When bumping the pin, change both `UV_VERSION` in the `justfile` and the
   `required-version` floor in `pyproject.toml` together.
 
+### Fixing a CVE in a transitive dependency
+
+When the `Dependency Audit` job flags a package VIP does not declare directly,
+raise a floor in `[tool.uv] constraint-dependencies` (for example
+`"urllib3>=2.8.0"`) and run `just relock`. The `Lockfile Guard` job rejects a
+`uv.lock` change that is not paired with a `pyproject.toml` change, and the
+constraint is that paired change. It also stops a later relock from resolving
+back to a vulnerable version.
+
 ### Resolving a uv.lock merge conflict
 
 Never hand-edit conflict markers in `uv.lock`. Take either side wholesale, then
diff --git a/pyproject.toml b/pyproject.toml
index a507e89b..6baf6858 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -151,6 +151,9 @@ build-backend = "hatchling.build"
 # floor rejects those versions for every uv command; `just relock` pins an exact
 # version on top of it. See docs/development.md ("The lockfile").
 required-version = ">=0.11"
+# urllib3 is transitive. Floor it at the first release that fixes
+# CVE-2026-97687/97688/97689 so a relock cannot resolve back to a vulnerable 2.7.x.
+constraint-dependencies = ["urllib3>=2.8.0"]
 
 [tool.hatch.build.targets.wheel]
 packages = ["src/vip", "src/vip_tests"]
diff --git a/uv.lock b/uv.lock
index d182b9a5..f86338ae 100644
--- a/uv.lock
+++ b/uv.lock
@@ -9,6 +9,9 @@ resolution-markers = [
     "python_full_version < '3.11'",
 ]
 
+[manifest]
+constraints = [{ name = "urllib3", specifier = ">=2.8.0" }]
+
 [[package]]
 name = "anyio"
 version = "4.15.1"
@@ -2628,11 +2631,11 @@ wheels = [
 
 [[package]]
 name = "urllib3"
-version = "2.7.0"
+version = "2.8.0"
 source = { registry = "https://pypi.org/simple" }
-sdist = { url = "https://files.pythonhosted.org/packages/53/0c/06f8b233b8fd13b9e5ee11424ef85419ba0d8ba0b3138bf360be2ff56953/urllib3-2.7.0.tar.gz", hash = "sha256:231e0ec3b63ceb14667c67be60f2f2c40a518cb38b03af60abc813da26505f4c", size = 433602, upload-time = "2026-05-07T16:13:18.596Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/e3/05/b17359e1cefb4f909b5e40b1b90a496d987258916dbbf88e842c729f510e/urllib3-2.8.0.tar.gz", hash = "sha256:63bf2ead4c879426ebf22ef2a781eeb4aa3b4ae798a0435506f8687fd5bb9b63", size = 458972, upload-time = "2026-09-15T19:29:36.253Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/7f/3e/5db95bcf282c52709639744ca2a8b149baccf648e39c8cc87553df9eae0c/urllib3-2.7.0-py3-none-any.whl", hash = "sha256:9fb4c81ebbb1ce9531cce37674bbc6f1360472bc18ca9a553ede278ef7276897", size = 131087, upload-time = "2026-05-07T16:13:17.151Z" },
+    { url = "https://files.pythonhosted.org/packages/92/9d/c4e665119135114480843e7ab388fa94d8480650450e6f8e26b70d323a4c/urllib3-2.8.0-py3-none-any.whl", hash = "sha256:0cf3cae568d36aa9576b28dfb35f11328f1cb974ca7647d9475ebb86c75ac6e3", size = 135717, upload-time = "2026-09-15T19:29:34.577Z" },
 ]
 
 [[package]]