{"answers":{"affected":"2 open source packages ship an affected version, including com.thoughtworks.xstream:xstream. It affects 4 products.","exploited":"There is no known exploitation of CVE-2020-26259 in the wild and no public exploit code.","fix":"Upgrade com.thoughtworks.xstream:xstream to 1.4.15 or later.","what":"CVE-2020-26259 is a medium-severity unsafe deserialization vulnerability in Apache Struts, published on 16 Dec 2020. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2020-26259 and fix it if it is affected.\n\nWhat it is: CVE-2020-26259 is a medium-severity unsafe deserialization vulnerability in Apache Struts, published on 16 Dec 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2020-26259 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- com.thoughtworks.xstream:xstream (Maven): affected all versions; fixed in 1.4.15\n- com.thoughtworks.xstream:xstream (Maven): affected all versions; fixed in 1.4.15\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-2020-26259/ (Markdown: https://insights.sbomify.com/CVE-2020-26259/index.md)","id":"CVE-2020-26259","markdown":"https://insights.sbomify.com/CVE-2020-26259/index.md","name":"CVE-2020-26259","record":{"aliases":["DEBIAN-CVE-2020-26259","GHSA-jfvx-7wrx-43fh","UBUNTU-CVE-2020-26259"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["data_modify"],"network_reachable":"yes","non_default_config":true,"product_category":"Java XML serialization library","requires_auth":"none","summary":"Remote attackers can delete arbitrary files on the host via crafted XML input when using XStream's default blacklist configuration.","user_interaction":"not_required","vuln_class":"deserialization"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"struts","vendor":"apache"},{"product":"debian_linux","vendor":"debian"},{"product":"fedora","vendor":"fedoraproject"},{"product":"xstream","vendor":"xstream"}],"cvss":{"score":6.8,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N","version":"3.1"},"cwes":[{"id":"CWE-78","name":"Improper Neutralization of Special Elements used in an OS Command"}],"description":"XStream is a Java library to serialize objects to XML and back again. In XStream before version 1.4.15, is vulnerable to an Arbitrary File Deletion on the local host when unmarshalling. The vulnerability may allow a remote attacker to delete arbitrary know files on the host as log as the executing process has sufficient rights only by manipulating the processed input stream. If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.15. The reported vulnerability does not exist running Java 15 or higher. No user is affected, who followed the recommendation to setup XStream's Security Framework with a whitelist! Anyone relying on XStream's default blacklist can immediately switch to a whilelist for the allowed types to avoid the vulnerability. Users of XStream 1.4.14 or below who still want to use XStream default blacklist can use a workaround described in more detailed in the referenced advisories.","ecosystems":["Maven"],"exploits":{"exploitdb":0,"first_seen":"2020-12-13","github_poc":3,"max_poc_stars":25,"metasploit":0,"nuclei":0,"refs":[{"date":"2020-12-13T17:39:11Z","kind":"github_poc","ref":"https://github.com/jas502n/CVE-2020-26259","stars":25,"title":"CVE-2020-26259: XStream is vulnerable to an Arbitrary File Deletion on the local host when unmarshalling as long as the executing process has sufficient rights."},{"date":"2021-01-22T09:23:28Z","kind":"github_poc","ref":"https://github.com/Al1ex/CVE-2020-26259","stars":1,"title":"CVE-2020-26259 \u0026\u0026XStream Arbitrary File Delete"},{"date":"2025-07-11T03:44:20Z","kind":"github_poc","ref":"https://github.com/cuijiung/xstream-CVE-2020-26259","stars":0,"title":null}],"tier":"poc_unverified"},"has_fix":true,"headline":"XStream is vulnerable to an Arbitrary File Deletion on the local host when unmarshalling","id":"CVE-2020-26259","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Maven","product":"apache:struts","products":["apache:struts","debian:debian_linux","fedoraproject:fedora"],"type":"deserialization","year":"2020"},"n_packages":2,"n_references":9,"next":{"headline":"Server Side Request Forgery in BookStack","id":"CVE-2020-26260"},"packages":[{"ecosystem":"Maven","fixed":["1.4.15"],"introduced":["0"],"last_affected":[],"package":"com.thoughtworks.xstream:xstream","purl":null,"source":"GHSA-jfvx-7wrx-43fh"},{"ecosystem":"Maven","fixed":["1.4.15"],"introduced":["0"],"last_affected":[],"package":"com.thoughtworks.xstream:xstream","purl":"pkg:maven/com.thoughtworks.xstream/xstream","source":"GHSA-jfvx-7wrx-43fh"}],"prev":{"headline":"Server-Side Forgery Request can be activated unmarshalling with XStream","id":"CVE-2020-26258"},"products":["xstream"],"published":"2020-12-16","related":[{"cvss_score":9.8,"headline":"Apache Struts Remote Code Execution","id":"CVE-2020-17530","kev_date_added":"2021-11-03","published":"2020-12-11"},{"cvss_score":9.8,"headline":"Apache Struts 1 Improper Input Validation","id":"CVE-2017-9791","kev_date_added":"2022-02-10","published":"2017-07-10"},{"cvss_score":9.8,"headline":"Apache Struts Remote Code Execution","id":"CVE-2017-5638","kev_date_added":"2021-11-03","published":"2017-03-11"},{"cvss_score":9.8,"headline":"Apache Struts 2 Improper Input Validation","id":"CVE-2012-0391","kev_date_added":"2022-01-21","published":"2012-01-08"},{"cvss_score":8.1,"headline":"Apache Struts Remote Code Execution","id":"CVE-2018-11776","kev_date_added":"2021-11-03","published":"2018-08-22"},{"cvss_score":8.1,"headline":"Apache Struts Deserialization of Untrusted Data","id":"CVE-2017-9805","kev_date_added":"2021-11-03","published":"2017-09-15"},{"cvss_score":8.1,"headline":"Apache Struts Command Injection","id":"CVE-2016-3081","kev_date_added":"2026-10-08","published":"2016-04-26"}],"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":"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)"},{"class":"open","licence":"CC0","name":"PoC-in-GitHub"}],"ssvc":{"automatable":"yes","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-10-07","vendors":["x-stream"]},"summary":"Remote attackers can delete arbitrary files on the host via crafted XML input when using XStream's default blacklist configuration.","url":"https://insights.sbomify.com/CVE-2020-26259/"}