{"answers":{"affected":"3 open source packages ship an affected version, including github.com/refraction-networking/utls. It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-27017 in the wild and no public exploit code.","fix":"Upgrade github.com/refraction-networking/utls to 1.8.1 or later.","what":"CVE-2026-27017 is a low-severity vulnerability in refraction-networking utls, published on 20 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-2026-27017 and fix it if it is affected.\n\nWhat it is: CVE-2026-27017 is a low-severity vulnerability in refraction-networking utls, published on 20 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-2026-27017 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- github.com/refraction-networking/utls (Go): affected from 1.6.0; fixed in 1.8.1\n- github.com/refraction-networking/utls (Go): affected from 1.6.0; fixed in 1.8.1\n- github.com/refraction-networking/utls (Go): affected from 1.6.0; fixed in 1.8.1\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-2026-27017/ (Markdown: https://insights.sbomify.com/CVE-2026-27017/index.md)","id":"CVE-2026-27017","markdown":"https://insights.sbomify.com/CVE-2026-27017/index.md","name":"CVE-2026-27017","record":{"aliases":["GHSA-7m29-f4hw-g2vx","GO-2026-4509","UBUNTU-CVE-2026-27017"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["security_bypass"],"network_reachable":"yes","non_default_config":true,"product_category":"Go TLS library","requires_auth":"none","summary":"uTLS library fails to mimic Chrome's GREASE ECH cipher suite selection, allowing fingerprinting detection of non-browser clients.","user_interaction":"required","vuln_class":"other"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"utls","vendor":"refraction-networking"}],"cvss":{"score":2.3,"severity":"low","source":"cna","vector":"CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N","version":"4.0"},"cwes":[{"id":"CWE-1240","name":"Use of a Cryptographic Primitive with a Risky Implementation"}],"description":"uTLS is a fork of crypto/tls, created to customize ClientHello for fingerprinting resistance while still using it for the handshake. Versions 1.6.0 through 1.8.0 contain a fingerprint mismatch with Chrome when using GREASE ECH, related to cipher suite selection. When Chrome selects the preferred cipher suite in the outer ClientHello and for ECH, it does so consistently based on hardware support—for example, if it prefers AES for the outer cipher suite, it also uses AES for ECH. However, the Chrome parrot in uTLS hardcodes AES preference for outer cipher suites but selects the ECH cipher suite randomly between AES and ChaCha20. This creates a 50% chance of selecting ChaCha20 for ECH while using AES for the outer cipher suite, a combination impossible in Chrome. This issue only affects GREASE ECH; in real ECH, Chrome selects the first valid cipher suite when AES is preferred, which uTLS handles correctly. This issue has been fixed in version 1.8.1.","ecosystems":["Go"],"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":"uTLS has a Chrome Parrot Fingerprint Vulnerability due to GREASE ECH Cipher Suite Mismatch","id":"CVE-2026-27017","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Go","product":null,"products":[],"type":"other","year":"2026"},"n_packages":3,"n_references":1,"next":{"headline":"Gotenberg: Chromium deny-list bypass via case-insensitive URL scheme","id":"CVE-2026-27018"},"packages":[{"ecosystem":"Go","fixed":["1.8.1"],"introduced":["1.6.0"],"last_affected":[],"package":"github.com/refraction-networking/utls","purl":null,"source":"GHSA-7m29-f4hw-g2vx"},{"ecosystem":"Go","fixed":["1.8.1"],"introduced":["1.6.0"],"last_affected":[],"package":"github.com/refraction-networking/utls","purl":"pkg:golang/github.com/refraction-networking/utls","source":"GHSA-7m29-f4hw-g2vx"},{"ecosystem":"Go","fixed":["1.8.1"],"introduced":["1.6.0"],"last_affected":[],"package":"github.com/refraction-networking/utls","purl":"pkg:golang/github.com/refraction-networking/utls","source":"GO-2026-4509"}],"prev":{"headline":"LibreNMS has Stored XSS in Custom OID - unit parameter missing strip_tags()","id":"CVE-2026-27016"},"products":["utls"],"published":"2026-02-20","related":[{"cvss_score":6.5,"headline":"uTLS ServerHellos are accepted without checking TLS 1.3 downgrade canaries","id":"CVE-2026-26994","kev_date_added":null,"published":"2026-02-20"}],"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":"Go Vulnerability Database","prefix":"GO"},{"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":"2026-02-20","vendors":["refraction-networking"]},"summary":"uTLS library fails to mimic Chrome's GREASE ECH cipher suite selection, allowing fingerprinting detection of non-browser clients.","url":"https://insights.sbomify.com/CVE-2026-27017/"}