{"id":"CVE-2026-110688","kind":"vulnerability","aliases":["CVE-2026-110688"],"related":[],"title":"Cpanel::JSON::XS: incremental parser lets a peer burn CPU with non-ASCII JSON","description":"Cpanel::JSON::XS versions from 4.51 before 4.80 for Perl allow quadratic CPU use by revalidating the remaining buffer per value in incr_parse.\n\nAt the first non-ASCII byte in a string, the decoder validates UTF-8 from there to the end of its input. incr_parse decodes each buffered value with a fresh decoder, so every value revalidates the rest of the buffer, and doubling the input quadruples the work.\n\nA peer that sends about a megabyte of ordinary non-ASCII JSON in one read ties up the process for seconds of CPU time.","summary":"Cpanel::JSON::XS versions 4.51 through 4.79 for Perl re-validate the rest of the input buffer for every value when incr_parse meets non-ASCII text, so CPU use grows with the square of the input size. A remote peer sending about a megabyte of ordinary non-ASCII JSON in one read can tie up the process for seconds, a denial of service.","severity":"medium","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["cpanel-json-xs","network-services","package","perl"],"not_affected_if":["no-incr-parse","trusted-input-only","version-outside-4.51-4.79"],"how_to_check":"- `perl -MCpanel::JSON::XS -e 'print $Cpanel::JSON::XS::VERSION'` to read the installed version\n- Search lockfiles and `cpanfile.snapshot` for `Cpanel::JSON::XS` and check whether the version falls between 4.51 and 4.79\n- Check whether the application calls `incr_parse` on data read from the network","fix":"- Upgrade Cpanel::JSON::XS to `4.80` or later\n- Rebuild and redeploy Perl services that bundle the module","status":"open","published_at":"2026-10-19T19:17:22+00:00","first_seen_at":"2026-10-23T21:57:18+00:00","triaged_at":"2026-10-25T05:10:42+00:00","updated_at":"2026-10-25T05:10:42+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-10-25T05:10:42Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Cpanel::JSON::XS to `4.80` or later\n- Rebuild and redeploy Perl services that bundle the module","reach":"network","title":"Cpanel::JSON::XS: incremental parser lets a peer burn CPU with non-ASCII JSON","impact":"low","summary":"Cpanel::JSON::XS versions 4.51 through 4.79 for Perl re-validate the rest of the input buffer for every value when incr_parse meets non-ASCII text, so CPU use grows with the square of the input size. A remote peer sending about a megabyte of ordinary non-ASCII JSON in one read can tie up the process for seconds, a denial of service.","category":"package","nicknames":[],"who_cares":["perl","cpanel-json-xs","network-services"],"confidence":0.6,"needs_auth":"no","worst_case":"Remote peer ties up CPU for seconds per request, causing denial of service","analyst_note":"","how_to_check":"- `perl -MCpanel::JSON::XS -e 'print $Cpanel::JSON::XS::VERSION'` to read the installed version\n- Search lockfiles and `cpanfile.snapshot` for `Cpanel::JSON::XS` and check whether the version falls between 4.51 and 4.79\n- Check whether the application calls `incr_parse` on data read from the network","needs_analyst":false,"not_affected_if":["version-outside-4.51-4.79","no-incr-parse","trusted-input-only"],"who_is_affected":"Perl applications that use Cpanel::JSON::XS incremental parsing (incr_parse) on data from untrusted peers, such as network services or stream readers that accept JSON from clients. Applications that only parse trusted local files or use the non-incremental decode path are less exposed. Teams not running Cpanel::JSON::XS in the 4.51 to 4.79 range can skip it.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000687,"input_tokens":3416,"output_tokens":690,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-110688':18A,21A '-2026':17A,20A '-8':136C '4.51':35B,103C '4.79':37B '4.80':105C 'allow':108C 'ascii':14A,58B,82B,127C,182C 'buffer':48B,116C,149C,163C 'burn':9A 'byte':128C 'cpanel':1A,23B,31B,98C 'cpanel-json-x':22B 'cpu':10A,61B,110C,194C 'cve':16A,19A 'decod':133C,147C,154C 'denial':95B 'doubl':165C 'end':141C 'everi':50B,156C 'first':124C 'fresh':153C 'grow':63B 'incr':53B,120C,145C 'increment':4A 'input':47B,69B,144C,167C 'json':2A,15A,24B,32B,83B,99C,183C 'let':6A 'meet':55B 'megabyt':77B,177C 'network':27B 'network-servic':26B 'non':13A,57B,81B,126C,181C 'non-ascii':12A,56B,80B,125C,180C 'one':85B,185C 'ordinari':79B,179C 'packag':29B 'pars':54B,121C,146C 'parser':5A 'peer':8A,73B,172C 'per':117C 'perl':30B,39B,107C 'process':91B,190C 'quadrat':109C 'quadrupl':168C 're':41B 're-valid':40B 'read':86B,186C 'remain':115C 'remot':72B 'rest':44B,160C 'revalid':113C,158C 'second':93B,192C 'send':74B,174C 'servic':28B,97B 'size':70B 'squar':66B 'string':131C 'text':59B 'tie':88B,187C 'time':195C 'use':62B,111C 'utf':135C 'valid':42B,134C 'valu':51B,118C,150C,157C 'version':34B,101C 'work':170C 'xs':3A,25B,33B,100C","nicknames":[],"mitigations":[],"who_affected":"Perl applications that use Cpanel::JSON::XS incremental parsing (incr_parse) on data from untrusted peers, such as network services or stream readers that accept JSON from clients. Applications that only parse trusted local files or use the non-incremental decode path are less exposed. Teams not running Cpanel::JSON::XS in the 4.51 to 4.79 range can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-19T19:17:22+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-110688","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-110688","severity":null,"published_at":"2026-10-19T19:17:22+00:00","modified_at":"2026-10-19T20:50:17+00:00","first_seen_at":"2026-10-23T21:57:18+00:00","fetched_at":"2026-10-23T22:28:57+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"}