{"id":"CVE-2026-120756","kind":"vulnerability","aliases":["CVE-2026-120756"],"related":[],"title":"HDF5: crafted file over-reads heap memory when opened","description":"HDF5 through 2.2.0 contains a heap buffer over-read vulnerability in H5O__chunk_deserialize() in src/H5Ocache.c. When decoding object header messages, the declared message size is checked against the end of the chunk image before the remainder of the message header (flags, and for version 2 object headers, the optional creation index) has been decoded. Because the message body begins after these fields, a message can start up to four bytes further into the chunk than the size check accounts for. A crafted HDF5 file can declare a message size that passes the check but extends past the end of the chunk image, causing the message’s decode callback, for example H5O__mtime_new_decode() in src/H5Omtime.c, to read beyond the heap allocation. The flaw is reachable during H5Fopen() on a crafted file. An attacker who can get a user or application to open a malicious file can cause a denial of service or limited disclosure of process memory.","summary":"HDF5 through 2.2.0 checks an object header message size before reading its flags and creation index, so a crafted file can make the library read past a heap buffer. An attacker who gets a user or application to open a malicious HDF5 file can crash the process or read limited process memory.","severity":"low","cvss":1.9,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["c","hdf5","package","python","scientific-computing"],"not_affected_if":["trusted-files-only"],"how_to_check":"- Check the installed HDF5 library version against the affected range (`through 2.2.0`).\n- Find where the application calls `H5Fopen()` on files that come from outside the organization.","fix":null,"status":"open","published_at":"2026-11-03T16:17:22+00:00","first_seen_at":"2026-11-03T16:21:42+00:00","triaged_at":"2026-11-03T16:24:29+00:00","updated_at":"2026-11-03T16:24:29+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-11-03T16:24:29Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"local","title":"HDF5: crafted file over-reads heap memory when opened","impact":"low","summary":"HDF5 through 2.2.0 checks an object header message size before reading its flags and creation index, so a crafted file can make the library read past a heap buffer. An attacker who gets a user or application to open a malicious HDF5 file can crash the process or read limited process memory.","audience":"developers","category":"package","nicknames":[],"who_cares":["hdf5","scientific-computing","python","c"],"confidence":0.7,"fix_status":"unknown","needs_auth":"no","worst_case":"process crashes or leaks limited memory contents","analyst_note":"","how_to_check":"- Check the installed HDF5 library version against the affected range (`through 2.2.0`).\n- Find where the application calls `H5Fopen()` on files that come from outside the organization.","plain_action":"","needs_analyst":false,"not_affected_if":["trusted-files-only"],"who_is_affected":"Applications and tools that open HDF5 files supplied by users or other systems can be exposed, since the flaw triggers during H5Fopen() on a crafted file. Systems that only open trusted, internally generated HDF5 files are much less exposed. The sources do not say which HDF5 release fixes it.","user_interaction":"yes","needs_special_setup":"unknown","severity_if_unknown":"low"},"cost_usd":0.000675,"input_tokens":4340,"output_tokens":483,"severity_before":"low"},"analyst_status":null,"analyst_note":null,"search":"'-120756':13A,16A '-2026':12A,15A '2':122C '2.2.0':26B,78C 'account':156C 'alloc':199C 'applic':60B,218C 'attack':54B,211C 'begin':136C 'beyond':196C 'bodi':135C 'buffer':52B,82C 'byte':147C 'c':17B 'callback':185C 'caus':180C,225C 'check':27B,103C,155C,170C 'chunk':89C,109C,151C,178C 'comput':23B 'contain':79C 'craft':2A,42B,159C,208C 'crash':68B 'creation':38B,127C 'cve':11A,14A 'declar':99C,163C 'decod':94C,131C,184C,191C 'denial':227C 'deseri':90C 'disclosur':232C 'end':106C,175C 'exampl':187C 'extend':172C 'field':139C 'file':3A,43B,66B,161C,209C,223C 'flag':36B,118C 'flaw':201C 'four':146C 'get':56B,214C 'h5fopen':205C 'h5o':88C,188C 'hdf5':1A,18B,24B,65B,76C,160C 'header':30B,96C,117C,124C 'heap':7A,51B,81C,198C 'imag':110C,179C 'index':39B,128C 'librari':47B 'limit':73B,231C 'make':45B 'malici':64B,222C 'memori':8A,75B,235C 'messag':31B,97C,100C,116C,134C,141C,165C,182C 'mtime':189C 'new':190C 'object':29B,95C,123C 'open':10A,62B,220C 'option':126C 'over-read':4A,83C 'packag':19B 'pass':168C 'past':49B,173C 'process':70B,74B,234C 'python':20B 'reachabl':203C 'read':6A,34B,48B,72B,85C,195C 'remaind':113C 'scientif':22B 'scientific-comput':21B 'servic':229C 'size':32B,101C,154C,166C 'src/h5ocache.c':92C 'src/h5omtime.c':193C 'start':143C 'user':58B,216C 'version':121C 'vulner':86C","nicknames":[],"mitigations":[],"who_affected":"Applications and tools that open HDF5 files supplied by users or other systems can be exposed, since the flaw triggers during H5Fopen() on a crafted file. Systems that only open trusted, internally generated HDF5 files are much less exposed. The sources do not say which HDF5 release fixes it.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"developers","plain_action":null,"pkeys":[],"ptokens":[],"labels":["c","hdf5","low","package","python","scientificcomputing"],"first_public_at":"2026-11-03T16:17:22+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/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":"0253b833-3e77-4dfe-9d57-17db1a2f0a74","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-120756","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-120756","severity":null,"published_at":"2026-11-03T16:17:22+00:00","modified_at":"2026-11-03T16:17:22+00:00","first_seen_at":"2026-11-03T16:21:42+00:00","fetched_at":"2026-11-03T16:21:42+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}