{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-12259 in the wild and no public exploit code.","fix":"Upgrade to a fixed version.","what":"CVE-2026-12259 is a medium-severity vulnerability in nltk/nltk, published on 3 Aug 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-2026-12259 and fix it if it is affected.\n\nWhat it is: CVE-2026-12259 is a medium-severity vulnerability in nltk/nltk, published on 3 Aug 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-2026-12259 in the wild and no public exploit code.\n\nAffected product: nltk/nltk. No package-level version data is available, so check the vendor advisory linked from the reference page.\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-2026-12259/ (Markdown: https://insights.sbomify.com/CVE-2026-12259/index.md)","id":"CVE-2026-12259","markdown":"https://insights.sbomify.com/CVE-2026-12259/index.md","name":"CVE-2026-12259","record":{"aliases":["DEBIAN-CVE-2026-12259","ECHO-34ff-644c-194f","UBUNTU-CVE-2026-12259"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["code_execution","data_modify"],"network_reachable":"yes","non_default_config":false,"product_category":"Python NLP library","requires_auth":"none","summary":"Attackers can install malicious packages by tampering with downloads before checksum validation, risking code execution in applications using nltk.","user_interaction":"required","vuln_class":"supply_chain"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"@huntr_ai","cpe":[{"product":"nltk","vendor":"nltk"}],"cvss":{"score":5.3,"severity":"medium","source":"cna","vector":"CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N","version":"3.0"},"cwes":[{"id":"CWE-494","name":"Download of Code Without Integrity Check"}],"description":"In nltk version 3.9.4, the `nltk.downloader.Downloader._download_package()` function writes downloaded package bytes to disk and may extract them before enforcing SHA-256 or MD5 checksum validation. This allows an attacker to tamper with the package response body for `info.url` through a compromised mirror, malicious proxy, or other source-substitution condition, leading to the installation of attacker-controlled package bytes. The vulnerability can result in malicious corpus or model content being trusted by downstream users or applications.","ecosystems":[],"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":"Improper Input Validation in nltk/nltk","id":"CVE-2026-12259","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"supply_chain","year":"2026"},"n_packages":0,"n_references":1,"next":{"headline":"SQL injection in the NetBoard CRM demo platform","id":"CVE-2026-12260"},"packages":[],"prev":{"headline":"Inadequate access control in the Hiperdino REST API","id":"CVE-2026-12258"},"products":["nltk/nltk"],"published":"2026-08-03","related":[{"cvss_score":10,"headline":"Arbitrary Code Execution in NLTK StanfordSegmenter via Untrusted JAR Loading","id":"CVE-2026-0848","kev_date_added":null,"published":"2026-03-05"},{"cvss_score":10,"headline":"Zip Slip Vulnerability in nltk/nltk Leading to Remote Code Execution","id":"CVE-2025-14009","kev_date_added":null,"published":"2026-02-18"},{"cvss_score":9.4,"headline":"NLTK before 3.10.0 Remote Code Execution via Unsafe Pickle Deserialization","id":"CVE-2026-78683","kev_date_added":null,"published":"2026-08-25"},{"cvss_score":9.3,"headline":"NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle Deserialization","id":"CVE-2026-79657","kev_date_added":null,"published":"2026-08-25"},{"cvss_score":9.3,"headline":"NLTK before 3.10.3 JVM Argument Injection via Per-Call Options","id":"CVE-2026-79675","kev_date_added":null,"published":"2026-08-25"},{"cvss_score":8.8,"headline":"NLTK 3.10.2 Path Traversal via corpus-reader constructors","id":"CVE-2026-79674","kev_date_added":null,"published":"2026-08-25"},{"cvss_score":8.7,"headline":"nltk PorterStemmer before 3.10.3 Quadratic-time DoS","id":"CVE-2026-81722","kev_date_added":null,"published":"2026-08-27"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"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":"2026-08-03","vendors":["nltk"]},"summary":"Attackers can install malicious packages by tampering with downloads before checksum validation, risking code execution in applications using nltk.","url":"https://insights.sbomify.com/CVE-2026-12259/"}