{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-44040 in the wild and no public exploit code.","fix":"No fix has been published for CVE-2026-44040 yet. Limit exposure of the affected software until one is available.","what":"CVE-2026-44040 is a medium-severity 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-2026-44040 and fix it if it is affected.\n\nWhat it is: CVE-2026-44040 is a medium-severity 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-2026-44040 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-2026-44040/ (Markdown: https://insights.sbomify.com/CVE-2026-44040/index.md)","id":"CVE-2026-44040","markdown":"https://insights.sbomify.com/CVE-2026-44040/index.md","name":"CVE-2026-44040","record":{"aliases":["GHSA-j37g-g7hg-vhg6"],"analysis":{"component_type":"desktop_application","fix_type":"no_fix_stated","impacts":["security_bypass","account_takeover"],"network_reachable":"yes","non_default_config":false,"product_category":"VNC remote control","requires_auth":"none","summary":"Attackers can predict VNC authentication challenges due to weak random number generation, potentially bypassing authentication or brute-forcing credentials.","user_interaction":"not_required","vuln_class":"weak_cryptography"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"securin","cpe":[{"product":"ultravnc","vendor":"uvnc"}],"cvss":{"score":4.8,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","version":"3.1"},"cwes":[{"id":"CWE-338","name":"Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)"}],"description":"UltraVNC through 1.8.2.2 uses a cryptographically weak pseudo-random number generator to produce VNC authentication challenge bytes. In rfb/vncauth.c:119-129, the vncRandomBytes() function seeds libc rand() with time(0) + getpid() + rand() and generates a 16-byte challenge. The combined seed space is approximately 31 bits (libc rand() internal state) and is entirely determined by publicly-observable values (wall-clock time and process ID). An attacker who can observe the authentication exchange can enumerate the seed space and predict the challenge within seconds, enabling forgery or offline brute-forcing of responses. Note: on Windows, the active code path may use vncEncryptBytes2.cpp which calls CryptGenRandom; reachability on shipped Windows binaries requires compile-graph verification and is under investigation.","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 vncauth.c uses time-seeded libc rand() to generate VNC authentication challenge bytes","id":"CVE-2026-44040","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"weak_cryptography","year":"2026"},"n_packages":0,"n_references":3,"next":{"headline":"UltraVNC vncWc2Mb calls wcslen() before validating that the wide string is NUL-terminated","id":"CVE-2026-44041"},"packages":[],"prev":{"headline":"Global buffer out-of-bounds read in DCMTK JPEG Huffman decoding","id":"CVE-2026-44038"},"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":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-07-09","vendors":["uvnc"]},"summary":"Attackers can predict VNC authentication challenges due to weak random number generation, potentially bypassing authentication or brute-forcing credentials.","url":"https://insights.sbomify.com/CVE-2026-44040/"}