{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-78207 in the wild and no public exploit code.","fix":"No fix has been published for CVE-2026-78207 yet. Limit exposure of the affected software until one is available.","what":"CVE-2026-78207 is a critical unsafe deserialization vulnerability in exceljs, published on 24 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-78207 and fix it if it is affected.\n\nWhat it is: CVE-2026-78207 is a critical unsafe deserialization vulnerability in exceljs, published on 24 Aug 2026. 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-2026-78207 in the wild and no public exploit code.\n\nAffected product: exceljs. 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-2026-78207/ (Markdown: https://insights.sbomify.com/CVE-2026-78207/index.md)","id":"CVE-2026-78207","markdown":"https://insights.sbomify.com/CVE-2026-78207/index.md","name":"CVE-2026-78207","record":{"aliases":["GHSA-3cpv-r8x3-29fp","GHSA-qwr4-7h29-chpf"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["code_execution","privilege_escalation"],"network_reachable":"yes","non_default_config":false,"product_category":"JavaScript Excel library","requires_auth":"none","summary":"Attackers can achieve remote code execution or privilege escalation via prototype pollution in exceljs when processing malicious cell notes.","user_interaction":"not_required","vuln_class":"deserialization"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"VulnCheck","cpe":[],"cvss":{"score":9.3,"severity":"critical","source":"cna","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N","version":"4.0"},"cwes":[{"id":"CWE-1321","name":"Improperly Controlled Modification of Object Prototype Attributes"}],"description":"exceljs through 4.4.0 contains a prototype pollution vulnerability in the deepMerge helper that fails to reject __proto__, constructor, or prototype keys when merging note objects. Attackers can assign parsed JSON with a malicious __proto__ property to cell notes, modifying Object.prototype and affecting all plain objects created in the process.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":false,"headline":"exceljs through 4.4.0 Prototype Pollution via deepMerge Reached From Note Serialization","id":"CVE-2026-78207","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"deserialization","year":"2026"},"n_packages":0,"n_references":4,"next":{"headline":"exceljs through 4.4.0 Path Traversal via Unvalidated addImage filename","id":"CVE-2026-78208"},"packages":[],"prev":{"headline":"exceljs through 4.4.0 Uncontrolled Resource Consumption via Unbounded xlsx Decompression","id":"CVE-2026-78206"},"products":["exceljs"],"published":"2026-08-24","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"yes","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-08-29","vendors":["exceljs"]},"summary":"Attackers can achieve remote code execution or privilege escalation via prototype pollution in exceljs when processing malicious cell notes.","url":"https://insights.sbomify.com/CVE-2026-78207/"}