security: bump urllib3 floor to 2.6.3 for CVE-2026-21441 - #1869
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FOSSA flagged CVE-2026-21441 (GHSA-38jv-5279-wg99, 8.9 High) against urllib3 2.6.0. The fix landed in urllib3 2.6.3: streaming decompression safeguards were bypassed when HTTP redirects were followed. The existing `urllib3>=2.6.0,<3` specifier already permits 2.6.3, but because 2.6.0 remains a resolvable install, Dependabot did not open a range-bump PR, and this repo did not have the security-updates side of Dependabot expressed in its config either. This change: * Raises the floor in pyproject.toml to `urllib3>=2.6.3,<3` so fresh resolves cannot land on a vulnerable release. * Adds `open-pull-requests-limit: 10` to both dependabot ecosystems so security PRs are not squeezed out by the default cap of 5, and documents on the pip block that security advisories fire independently of the weekly schedule as long as "Dependabot security updates" is enabled under Settings -> Code security. * Adds a CHANGELOG entry naming the CVE and GHSA. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
stephendeoca
approved these changes
Aug 21, 2026
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Summary
FOSSA flagged CVE-2026-21441 (GHSA-38jv-5279-wg99, 8.9 High) against urllib3 2.6.0. The fix landed in urllib3 2.6.3: streaming decompression safeguards were bypassed when HTTP redirects were followed.
The existing
urllib3>=2.6.0,<3specifier inpyproject.tomlalready permits 2.6.3, but because 2.6.0 remains a resolvable install, Dependabot did not open a range-bump PR, and the repo did not have Dependabot's security-updates side expressed in its config either. This PR closes that gap.Changes
pyproject.toml— raise the urllib3 floor tourllib3>=2.6.3,<3so fresh resolves cannot land on a vulnerable release. The<3upper bound is unchanged; this is a floor bump within the existing supported range..github/dependabot.yml— addopen-pull-requests-limit: 10to both the pip and github-actions ecosystems so security PRs are not squeezed out by the default cap of 5. Add a comment on the pip block noting that security advisories fire independently of the weekly schedule as long as "Dependabot security updates" is enabled under Settings -> Code security.CHANGELOG.md— add an## Unreleasedbullet naming the CVE, the GHSA, and the reason for the bump.Notes
TSC's manual redirect walker (#1848) disables urllib3's built-in follower on new code paths, but downstream callers using urllib3 directly (and TSC endpoints that predate #1848) still relied on the built-in path — so the floor bump closes the gap for all callers rather than only the paths already touched by #1848.
Test plan
python -c "import tomllib; tomllib.loads(open('pyproject.toml', 'rb').read().decode())"parses.python -c "import yaml; yaml.safe_load(open('.github/dependabot.yml'))"parses.Generated with Claude Code