{"id":"CVE-2026-120456","kind":"vulnerability","aliases":["CVE-2026-120456"],"related":[],"title":"L-SMASH: crafted MP4 files corrupt heap memory and crash apps","description":"L-SMASH through 2.14.5 contains a heap out-of-bounds write vulnerability in isom_read_hdlr() and isom_read_dref_entry() in core/read.c triggered by oversized box sizes. Attackers can supply crafted MP4 or MOV files declaring hdlr or url box sizes larger than remaining data, stalling the stream position and corrupting heap memory to crash applications.","summary":"L-SMASH is a library for reading and writing MP4 and MOV media files. A crafted file with oversized box sizes makes the parser write past a heap buffer, corrupting memory and crashing the application that opens it.","severity":"medium","cvss":6.9,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["l-smash","media-processing","mov","mp4","package"],"not_affected_if":["library-not-used","no-untrusted-media"],"how_to_check":"- Check whether the `L-SMASH` library (liblsmash) is linked into any application or build you run, for example with `ldd` on the binary or by searching the dependency manifest.\n- Confirm the installed version against the range in the sources: through `2.14.5`.","fix":null,"status":"open","published_at":"2026-11-02T15:17:29+00:00","first_seen_at":"2026-11-02T15:24:03+00:00","triaged_at":"2026-11-02T15:26:07+00:00","updated_at":"2026-11-02T15:26:07+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-11-02T15:26:07Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"local","title":"L-SMASH: crafted MP4 files corrupt heap memory and crash apps","impact":"medium","summary":"L-SMASH is a library for reading and writing MP4 and MOV media files. A crafted file with oversized box sizes makes the parser write past a heap buffer, corrupting memory and crashing the application that opens it.","audience":"developers","category":"package","nicknames":[],"who_cares":["l-smash","media-processing","mp4","mov"],"confidence":0.6,"fix_status":"unknown","needs_auth":"no","worst_case":"Crafted media file crashes the application parsing it","analyst_note":"Sources do not name the fixed version; check the linked patch at github.com and the vulncheck advisory for the release that fixes it.","how_to_check":"- Check whether the `L-SMASH` library (liblsmash) is linked into any application or build you run, for example with `ldd` on the binary or by searching the dependency manifest.\n- Confirm the installed version against the range in the sources: through `2.14.5`.","plain_action":"","needs_analyst":true,"not_affected_if":["no-untrusted-media","library-not-used"],"who_is_affected":"Applications that embed L-SMASH to parse MP4 or MOV files, especially those that open media from untrusted sources such as uploads or downloads. Systems that never parse media with this library can skip it. The sources do not name a fixed version, though a patch link is listed.","user_interaction":"yes","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000691,"input_tokens":4202,"output_tokens":541,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-120456':15A,18A '-2026':14A,17A '2.14.5':70C 'app':12A 'applic':63B,124C 'attack':96C 'bound':77C 'box':48B,94C,108C 'buffer':57B 'contain':71C 'core/read.c':90C 'corrupt':7A,58B,119C 'craft':4A,44B,99C 'crash':11A,61B,123C 'cve':13A,16A 'data':113C 'declar':104C 'dref':87C 'entri':88C 'file':6A,42B,45B,103C 'hdlr':83C,105C 'heap':8A,56B,73C,120C 'isom':81C,85C 'l':2A,20B,29B,67C 'l-smash':1A,19B,28B,66C 'larger':110C 'librari':33B 'make':50B 'media':23B,41B 'media-process':22B 'memori':9A,59B,121C 'mov':25B,40B,102C 'mp4':5A,26B,38B,100C 'open':65B 'out-of-bound':74C 'overs':47B,93C 'packag':27B 'parser':52B 'past':54B 'posit':117C 'process':24B 'read':35B,82C,86C 'remain':112C 'size':49B,95C,109C 'smash':3A,21B,30B,68C 'stall':114C 'stream':116C 'suppli':98C 'trigger':91C 'url':107C 'vulner':79C 'write':37B,53B,78C","nicknames":[],"mitigations":[],"who_affected":"Applications that embed L-SMASH to parse MP4 or MOV files, especially those that open media from untrusted sources such as uploads or downloads. Systems that never parse media with this library can skip it. The sources do not name a fixed version, though a patch link is listed.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"developers","plain_action":null,"pkeys":[],"ptokens":[],"labels":["lsmash","mediaprocessing","medium","mov","mp4","package"],"first_public_at":"2026-11-02T15:17:29+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"disclosure@vulncheck.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-120456","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-120456","severity":null,"published_at":"2026-11-02T15:17:29+00:00","modified_at":"2026-11-02T15:17:29+00:00","first_seen_at":"2026-11-02T15:24:03+00:00","fetched_at":"2026-11-02T15:24:03+00:00","note":null}],"documents":[{"id":52509,"url":"https://github.com/l-smash/l-smash/commit/805ee3c9632e054198d3cb5b09c7b7aa36cdd791","title":"Patch: github.com","kind":"other","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Patch: github.com"},{"id":52510,"url":"https://www.vulncheck.com/advisories/l-smash-through-2.14.5-heap-out-of-bounds-write-via-hdlr-and-url-boxes","title":"Third-party advisory: www.vulncheck.com","kind":"advisory","source":"nvd","publisher":"research","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":"Third-party advisory: www.vulncheck.com"}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}