{"answers":{"affected":"3 open source packages ship an affected version, including flask. It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-27205 in the wild and no public exploit code.","fix":"Upgrade flask to 3.1.3 or later.","what":"CVE-2026-27205 is a low-severity vulnerability in pallets flask, published on 21 Feb 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link."},"fix_prompt":"Check this codebase for CVE-2026-27205 and fix it if it is affected.\n\nWhat it is: CVE-2026-27205 is a low-severity vulnerability in pallets flask, published on 21 Feb 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.\nExploitation: There is no known exploitation of CVE-2026-27205 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- flask (PyPI): affected all versions; fixed in 3.1.3\n- flask (PyPI): affected all versions; fixed in 3.1.3\n- flask (PyPI): affected all versions; fixed in 3.1.3\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-27205/ (Markdown: https://insights.sbomify.com/CVE-2026-27205/index.md)","id":"CVE-2026-27205","markdown":"https://insights.sbomify.com/CVE-2026-27205/index.md","name":"CVE-2026-27205","record":{"aliases":["CLEANSTART-2026-BX07210","CLEANSTART-2026-UA33739","CLSA-2026-1789727592","CLSA-2026-1789986000","CLSA-2026-1789986625","DEBIAN-CVE-2026-27205","ECHO-32c7-8a8f-5df3","GHSA-68rp-wp8r-4726","MINI-8f6h-66c5-7cf4","MINI-pjv3-39p6-hx9v","OESA-2026-2135","OESA-2026-2136","OESA-2026-2137","PYSEC-2026-2151","ROOT-APP-PYPI-CVE-2026-27205","SUSE-SU-2026:0849-1","SUSE-SU-2026:22023-1","UBUNTU-CVE-2026-27205","USN-8104-1","openSUSE-SU-2026:10264-1","openSUSE-SU-2026:20885-1"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["data_read"],"network_reachable":"yes","non_default_config":true,"product_category":"Flask web framework","requires_auth":"none","summary":"Attackers can read sensitive session data from caches if Flask is behind a misconfigured proxy and session keys are accessed without values.","user_interaction":"required","vuln_class":"information_disclosure"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"flask","vendor":"palletsprojects"}],"cvss":{"score":2.3,"severity":"low","source":"cna","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N","version":"4.0"},"cwes":[{"id":"CWE-524","name":"Use of Cache Containing Sensitive Information"}],"description":"Flask is a web server gateway interface (WSGI) web application framework. In versions 3.1.2 and below, when the session object is accessed, Flask should set the Vary: Cookie header., resulting in a Use of Cache Containing Sensitive Information vulnerability. The logic instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked. The severity and risk depend on the application being hosted behind a caching proxy that doesn't ignore responses with cookies, not setting a Cache-Control header to mark pages as private or non-cacheable, and accessing the session in a way that only touches keys without reading values or mutating the session. The issue has been fixed in version 3.1.3.","ecosystems":["PyPI","SUSE:Linux Enterprise Module for Python 3 15 SP7","SUSE:Linux Enterprise Server 16.0","SUSE:Linux Enterprise Server for SAP applications 16.0","openSUSE:Leap 15.6","openSUSE:Tumbleweed"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"Flask session does not add `Vary: Cookie` header when accessed in some ways","id":"CVE-2026-27205","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"PyPI","product":null,"products":[],"type":"information_disclosure","year":"2026"},"n_packages":8,"n_references":3,"next":{"headline":"Zumba Json Serializer has a potential PHP Object Injection via Unrestricted @type in unserialize()","id":"CVE-2026-27206"},"packages":[{"ecosystem":"PyPI","fixed":["3.1.3"],"introduced":["0"],"last_affected":[],"package":"flask","purl":null,"source":"GHSA-68rp-wp8r-4726"},{"ecosystem":"PyPI","fixed":["3.1.3"],"introduced":["0"],"last_affected":[],"package":"flask","purl":"pkg:pypi/flask","source":"GHSA-68rp-wp8r-4726"},{"ecosystem":"PyPI","fixed":["3.1.3"],"introduced":["0"],"last_affected":[],"package":"flask","purl":"pkg:pypi/flask","source":"PYSEC-2026-2151"},{"ecosystem":"SUSE:Linux Enterprise Module for Python 3 15 SP7","fixed":["2.3.2-150400.3.9.1"],"introduced":["0"],"last_affected":[],"package":"python-Flask","purl":"pkg:rpm/suse/python-Flask\u0026distro=SUSE%20Linux%20Enterprise%20Module%20for%20Python%203%2015%20SP7","source":"SUSE-SU-2026:0849-1"},{"ecosystem":"SUSE:Linux Enterprise Server 16.0","fixed":["3.1.1-160000.3.1"],"introduced":["0"],"last_affected":[],"package":"python-Flask","purl":"pkg:rpm/suse/python-Flask\u0026distro=SUSE%20Linux%20Enterprise%20Server%2016.0","source":"SUSE-SU-2026:22023-1"},{"ecosystem":"SUSE:Linux Enterprise Server for SAP applications 16.0","fixed":["3.1.1-160000.3.1"],"introduced":["0"],"last_affected":[],"package":"python-Flask","purl":"pkg:rpm/suse/python-Flask\u0026distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20applications%2016.0","source":"SUSE-SU-2026:22023-1"},{"ecosystem":"openSUSE:Leap 15.6","fixed":["2.3.2-150400.3.9.1"],"introduced":["0"],"last_affected":[],"package":"python-Flask","purl":"pkg:rpm/opensuse/python-Flask\u0026distro=openSUSE%20Leap%2015.6","source":"SUSE-SU-2026:0849-1"},{"ecosystem":"openSUSE:Tumbleweed","fixed":["3.1.3-1.1"],"introduced":["0"],"last_affected":[],"package":"python-Flask","purl":"pkg:rpm/opensuse/python-Flask\u0026distro=openSUSE%20Tumbleweed","source":"openSUSE-SU-2026:10264-1"}],"prev":{"headline":"Wasmtime WASI implementations are vulnerable to guest-controlled resource exhaustion","id":"CVE-2026-27204"},"products":["flask"],"published":"2026-02-21","related":[{"cvss_score":7.5,"headline":"Flask vulnerable to possible disclosure of permanent session cookie due to missing Vary: Cookie header","id":"CVE-2023-30861","kev_date_added":null,"published":"2023-05-02"},{"cvss_score":7.5,"headline":"Pallets Project Flask is vulnerable to Denial of Service via Unexpected memory usage","id":"CVE-2019-1010083","kev_date_added":null,"published":"2019-07-17"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"class":"attribution","licence":"CC BY 4.0","name":"PyPA Advisory Database","prefix":"PYSEC"},{"class":"attribution","licence":"CC BY 4.0","name":"SUSE","prefix":"SUSE"},{"class":"attribution","licence":"CC BY 4.0","name":"SUSE","prefix":"openSUSE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-02-24","vendors":["pallets"]},"summary":"Attackers can read sensitive session data from caches if Flask is behind a misconfigured proxy and session keys are accessed without values.","url":"https://insights.sbomify.com/CVE-2026-27205/"}