{"id":"CVE-2026-118129","kind":"vulnerability","aliases":["CVE-2026-118129"],"related":[],"title":"Chitchatter: postMessage config check lets attackers bypass authentication remotely","description":"A vulnerability was found in jeremyckahn Chitchatter up to f82538633813c854a81a8b2112a2f6ba17b39cbc. The affected element is the function isConfigMessageEvent of the file src/Bootstrap.tsx of the component PostMessage Handler. Performing a manipulation of the argument parentDomain results in improper authentication. Remote exploitation of the attack is possible. The exploit has been made public and could be used. This product follows a rolling release approach for continuous delivery, so version details for affected or updated releases are not provided. The patch is named e3babb5cd83bfe3b99f1d82358ac5c1ea8e8a688. It is recommended to apply a patch to fix this issue. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.","summary":"Chitchatter's postMessage handler in src/Bootstrap.tsx accepts configuration messages from an improperly validated parentDomain argument, so authentication can be bypassed. A remote attacker can send forged configuration messages, and a public exploit exists.","severity":"high","cvss":7.5,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["chitchatter","other","self-hosted","web-app"],"not_affected_if":["patched-build"],"how_to_check":"- Confirm the deployed build includes commit `e3babb5cd83bfe3b99f1d82358ac5c1ea8e8a688` (for example, `git merge-base --is-ancestor e3babb5cd83bfe3b99f1d82358ac5c1ea8e8a688 HEAD` in the deployed checkout)\n- Review `isConfigMessageEvent` in `src/Bootstrap.tsx` for the parentDomain check\n- Check the deployed version against the upstream repository; the sources give no release version because the project uses rolling releases","fix":"- Update Chitchatter to a build that includes commit `e3babb5cd83bfe3b99f1d82358ac5c1ea8e8a688` or later\n- Redeploy the web app after the update, since it is a rolling release with no version number to pin","status":"open","published_at":"2026-10-28T00:17:11+00:00","first_seen_at":"2026-10-28T00:29:54+00:00","triaged_at":"2026-10-28T00:31:38+00:00","updated_at":"2026-10-28T00:31:38+00:00","category":"other","confidence":0.6,"triage":{"at":"2026-10-28T00:31:38Z","model":"claude-haiku-5-5","output":{"fix":"- Update Chitchatter to a build that includes commit `e3babb5cd83bfe3b99f1d82358ac5c1ea8e8a688` or later\n- Redeploy the web app after the update, since it is a rolling release with no version number to pin","reach":"internet","title":"Chitchatter: postMessage config check lets attackers bypass authentication remotely","impact":"high","summary":"Chitchatter's postMessage handler in src/Bootstrap.tsx accepts configuration messages from an improperly validated parentDomain argument, so authentication can be bypassed. A remote attacker can send forged configuration messages, and a public exploit exists.","category":"other","nicknames":[],"who_cares":["chitchatter","web-app","self-hosted"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Unknown: sources do not say what a forged configuration message changes.","analyst_note":"Check the upstream fix commit e3babb5cd83bfe3b99f1d82358ac5c1ea8e8a688 and the public exploit to confirm what an attacker can change and whether user interaction is needed.","how_to_check":"- Confirm the deployed build includes commit `e3babb5cd83bfe3b99f1d82358ac5c1ea8e8a688` (for example, `git merge-base --is-ancestor e3babb5cd83bfe3b99f1d82358ac5c1ea8e8a688 HEAD` in the deployed checkout)\n- Review `isConfigMessageEvent` in `src/Bootstrap.tsx` for the parentDomain check\n- Check the deployed version against the upstream repository; the sources give no release version because the project uses rolling releases","needs_analyst":true,"not_affected_if":["patched-build"],"who_is_affected":"Deployments of Chitchatter up to commit `f82538633813c854a81a8b2112a2f6ba17b39cbc` are affected, because the postMessage handler does not properly validate the parentDomain argument. Teams running a current build that includes the fix commit can skip it. The sources do not say what configuration an attacker gains by forging the message.","user_interaction":"unknown","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.001251,"input_tokens":3502,"output_tokens":1802,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-118129':12A,15A '-2026':11A,14A 'accept':30B 'affect':68C,125C,167C 'app':23B 'appli':141C 'approach':117C 'argument':38B,88C 'attack':6A,46B,98C 'authent':8A,40B,93C 'bypass':7A,43B 'check':4A 'chitchatt':1A,16B,24B,63C 'compon':80C 'config':3A 'configur':31B,50B 'contact':151C 'continu':119C 'could':108C 'cve':10A,13A 'deliveri':120C 'detail':123C 'e3babb5cd83bfe3b99f1d82358ac5c1ea8e8a688':136C 'earli':152C 'element':69C 'exist':56B 'exploit':55B,95C,102C 'f82538633813c854a81a8b2112a2f6ba17b39cbc':66C 'file':76C 'fix':145C,163C 'follow':113C 'forg':49B 'found':60C 'function':72C 'handler':27B,82C 'host':20B 'improp':35B,92C 'isconfigmessageev':73C 'issu':147C 'jeremyckahn':62C 'let':5A 'made':105C 'manipul':85C 'manner':158C 'messag':32B,51B 'name':135C 'parentdomain':37B,89C 'patch':133C,143C 'perform':83C 'possibl':100C 'postmessag':2A,26B,81C 'product':112C,168C 'profession':157C 'provid':131C 'public':54B,106C 'quick':160C 'recommend':139C 'releas':116C,128C,161C 'remot':9A,45B,94C 'respond':153C 'result':90C 'roll':115C 'self':19B 'self-host':18B 'send':48B 'src/bootstrap.tsx':29B,77C 'updat':127C 'use':110C 'valid':36B 'vendor':149C 'version':122C,164C 'vulner':58C 'web':22B 'web-app':21B","nicknames":[],"mitigations":[],"who_affected":"Deployments of Chitchatter up to commit `f82538633813c854a81a8b2112a2f6ba17b39cbc` are affected, because the postMessage handler does not properly validate the parentDomain argument. Teams running a current build that includes the fix commit can skip it. The sources do not say what configuration an attacker gains by forging the message.","tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-28T00:17:11+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/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":"cna@vuldb.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-118129","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-118129","severity":null,"published_at":"2026-10-28T00:17:11+00:00","modified_at":"2026-10-28T00:17:11+00:00","first_seen_at":"2026-10-28T00:29:54+00:00","fetched_at":"2026-10-28T00:29:54+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"}