{"id":"CVE-2021-21330","aliases":["GHSA-v6wp-4m6f-gcjg","PYSEC-2021-76"],"title":"`aiohttp` Open Redirect vulnerability (`normalize_path_middleware` middleware)","summary":"`aiohttp` Open Redirect vulnerability (`normalize_path_middleware` middleware)","severity":"low","cvss":3.1,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N","vendor":"aiohttp","product":"aiohttp","ecosystem":"pip","affected":["aiohttp < 3.7.4"],"patched":["aiohttp 3.7.4"],"published":"2021-02-26","updated":"2026-07-08","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-v6wp-4m6f-gcjg","references":[{"url":"https://github.com/aio-libs/aiohttp/security/advisories/GHSA-v6wp-4m6f-gcjg"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-21330"},{"url":"https://github.com/aio-libs/aiohttp/commit/2545222a3853e31ace15d87ae0e2effb7da0c96b"},{"url":"https://github.com/aio-libs/aiohttp"},{"url":"https://github.com/aio-libs/aiohttp/blob/master/CHANGES.rst#374-2021-02-25"},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/aiohttp/PYSEC-2021-76.yaml"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FU7ENI54JNEK3PHEFGCE46DGMFNTVU6L"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JN3V7CZJRT4QFCVXB6LDPCJH7NAOFCA5"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FU7ENI54JNEK3PHEFGCE46DGMFNTVU6L"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/JN3V7CZJRT4QFCVXB6LDPCJH7NAOFCA5"},{"url":"https://pypi.org/project/aiohttp"},{"url":"https://security.gentoo.org/glsa/202208-19"},{"url":"https://www.debian.org/security/2021/dsa-4864"}],"tags":["osv","pip"],"epss":0.01905,"epssPercentile":0.78841,"ingestedAt":"2026-07-08T18:25:53.109Z","slug":"CVE-2021-21330","body":"## Overview\n\n### Impact\n\nOpen redirect vulnerability — a maliciously crafted link to an aiohttp-based web-server could redirect the browser to a different website.\n\nIt is caused by a bug in the `aiohttp.web_middlewares.normalize_path_middleware` middleware.\n\n### Patches\n\nThis security problem has been fixed in v3.7.4. Upgrade your dependency as follows:\n[`pip install aiohttp >= 3.7.4`]\n\n### Workarounds\n\nIf upgrading is not an option for you, a workaround can be to avoid using `aiohttp.web_middlewares.normalize_path_middleware` in your applications.\n\n### References\n\n* [aiohttp @ PyPI]\n* [GHSA-v6wp-4m6f-gcjg]\n* [OWASP page on open redirects]\n\n### For more information\n\nIf you have any questions or comments about this advisory:\n* Open an issue in the [aiohttp repo](https://github.com/aio-libs/aiohttp/issues/new/choose)\n* Email us at wk+aio-libs-security@sydorenko.org.ua and/or andrew.svetlov+aio-libs-security@gmail.com\n\nCredit: [Jelmer Vernooij] and [Beast Glatisant].\n\n[aiohttp @ PyPI]: https://pypi.org/p/aiohttp\n[`pip install aiohttp >= 3.7.4`]: https://pypi.org/project/aiohttp/3.7.4/\n[GHSA-v6wp-4m6f-gcjg]: https://github.com/aio-libs/aiohttp/security/advisories/GHSA-v6wp-4m6f-gcjg\n[OWASP page on open redirects]:\nhttps://cheatsheetseries.owasp.org/cheatsheets/Unvalidated_Redirects_and_Forwards_Cheat_Sheet.html\n\n[Jelmer Vernooij]: https://jelmer.uk\n[Beast Glatisant]: https://github.com/g147\n\n## Affected packages\n\n- `aiohttp < 3.7.4`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `aiohttp 3.7.4`","depth":"sunlit","depthScore":17,"depthScoreParts":{"impact":17.1,"likelihood":0.4,"exploitation":0,"ransomware":0},"changes":[]}