{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-7840 in the wild and no public exploit code.","fix":"No fix has been published for CVE-2026-7840 yet. Limit exposure of the affected software until one is available.","what":"CVE-2026-7840 is a critical memory corruption vulnerability in uvnc UltraVNC, published on 1 Jul 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-2026-7840 and fix it if it is affected.\n\nWhat it is: CVE-2026-7840 is a critical memory corruption vulnerability in uvnc UltraVNC, published on 1 Jul 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-2026-7840 in the wild and no public exploit code.\n\nAffected product: uvnc UltraVNC. 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-2026-7840/ (Markdown: https://insights.sbomify.com/CVE-2026-7840/index.md)","id":"CVE-2026-7840","markdown":"https://insights.sbomify.com/CVE-2026-7840/index.md","name":"CVE-2026-7840","record":{"aliases":["GHSA-95qw-xpp9-h343"],"analysis":{"component_type":"server_software","fix_type":"upgrade","impacts":["code_execution"],"network_reachable":"yes","non_default_config":false,"product_category":"VNC repeater server","requires_auth":"none","summary":"Unauthenticated remote attackers can achieve arbitrary code execution on UltraVNC repeater servers via a buffer overflow in the embedded HTTP administration server.","user_interaction":"not_required","vuln_class":"memory_corruption"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"securin","cpe":[{"product":"ultravnc","vendor":"uvnc"}],"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:H/SC:N/SI:N/SA:N","version":"4.0"},"cwes":[{"id":"CWE-787","name":"Out-of-bounds Write"}],"description":"UltraVNC repeater through 1.8.2.2 contains a global buffer overflow in its embedded HTTP administration server. The functions wi_senderr() and wi_replyhdr() in repeater/webgui/webutils.c write the caller-supplied HTTP request URI into a fixed 1000-byte global buffer (hdrbuf) via unchecked sprintf calls. The HTTP receive buffer accepts URIs up to approximately 150 KB (WI_RXBUFSIZE = 153600), so an unauthenticated attacker who can reach the repeater HTTP port (default TCP 80) can overflow hdrbuf by at least 500 bytes with a single HTTP request containing a URI of 1500 bytes or longer, corrupting adjacent .bss-segment globals. The overflow occurs before any authentication check, making it reachable without credentials. A remote, unauthenticated attacker can achieve arbitrary code execution on the host running the repeater.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":null,"headline":"UltraVNC repeater HTTP server global buffer overflow via long URI (pre-auth RCE)","id":"CVE-2026-7840","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"memory_corruption","year":"2026"},"n_packages":0,"n_references":3,"next":{"headline":"GV-ASWeb Remote Code Execution (RCE) vulnerability","id":"CVE-2026-7841"},"packages":[],"prev":{"headline":"UltraVNC repeater ships hardcoded default admin password allowing unauthenticated admin access","id":"CVE-2026-7839"},"products":["UltraVNC"],"published":"2026-07-01","related":[{"cvss_score":9.8,"headline":"Memory corruption in UltraVNC","id":"CVE-2019-8264","kev_date_added":null,"published":"2019-03-09"},{"cvss_score":9.8,"headline":"Memory corruption in UltraVNC","id":"CVE-2019-8265","kev_date_added":null,"published":"2019-03-09"},{"cvss_score":9.8,"headline":"Memory corruption in UltraVNC","id":"CVE-2019-8266","kev_date_added":null,"published":"2019-03-09"},{"cvss_score":9.8,"headline":"Memory corruption in UltraVNC","id":"CVE-2019-8280","kev_date_added":null,"published":"2019-03-09"},{"cvss_score":9.8,"headline":"Memory corruption in UltraVNC","id":"CVE-2018-15361","kev_date_added":null,"published":"2019-03-05"},{"cvss_score":9.8,"headline":"Integer overflow in UltraVNC","id":"CVE-2019-8260","kev_date_added":null,"published":"2019-03-05"},{"cvss_score":9.8,"headline":"Integer overflow in UltraVNC","id":"CVE-2019-8261","kev_date_added":null,"published":"2019-03-05"}],"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":"yes","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-07-09","vendors":["uvnc"]},"summary":"Unauthenticated remote attackers can achieve arbitrary code execution on UltraVNC repeater servers via a buffer overflow in the embedded HTTP administration server.","url":"https://insights.sbomify.com/CVE-2026-7840/"}