178 lines
11 KiB
JSON
178 lines
11 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-71886",
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"assignerOrgId": "91579145-5d7b-4cc5-b925-a0262ff19630",
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"state": "PUBLISHED",
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"assignerShortName": "bcorg",
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"dateReserved": "2026-08-08T00:06:06.982Z",
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"datePublished": "2026-10-03T08:46:33.868Z",
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"dateUpdated": "2026-10-05T16:03:23.403Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "91579145-5d7b-4cc5-b925-a0262ff19630",
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"shortName": "bcorg",
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"dateUpdated": "2026-10-03T08:46:33.868Z"
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},
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"title": "OpenPGP certification accepted from a subkey without certification authority",
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"problemTypes": [
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{
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"descriptions": [
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{
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"lang": "en",
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"cweId": "CWE-863",
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"description": "CWE-863 Incorrect Authorization",
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"type": "CWE"
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},
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{
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"lang": "en",
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"cweId": "CWE-285",
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"description": "CWE-285 Improper Authorization",
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"type": "CWE"
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}
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]
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}
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],
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"affected": [
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{
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"vendor": "Legion of the Bouncy Castle Inc.",
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"product": "BC-JAVA",
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"platforms": [
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"all"
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],
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"collectionURL": "https://www.bouncycastle.org/download/bouncy-castle-java/",
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"packageName": "bcpg",
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"repo": "https://github.com/bcgit/bc-java",
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"packageURL": "pkg:maven/org.bouncycastle/bcpg-jdk18on",
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"modules": [
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"pg"
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],
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"programFiles": [
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"OpenPGPCertificate"
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],
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"versions": [
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{
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"status": "affected",
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"version": "1.81",
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"lessThan": "1.86",
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"versionType": "maven"
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}
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],
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"defaultStatus": "unaffected"
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}
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],
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"descriptions": [
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{
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"lang": "en",
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"value": "In Bouncy Castle for Java before 1.86, the high-level OpenPGP certificate API accepted a third-party certification or trust delegation from any component key of the issuing certificate, without requiring that component to have been granted the authority to certify. OpenPGPCertificate.getCertificationBy() and getDelegationBy() resolve a third-party signature by matching its issuer key identifier against every key of the third-party certificate, then verify the issuing component's binding chain and the signature itself; nothing checked that the issuing component carried the RFC 9580 sec. 5.2.3.29 certification key flag (CERTIFY_OTHER) when the signature was created. A subkey bound only with SIGN_DATA - the online signing subkey of exactly the offline-primary arrangement those key flags exist to express - could therefore issue a positive User ID certification over an attacker-controlled identity, or a full-trust depth-one direct-key delegation of introducer trust, and the API returned it as a valid signature chain attributed to the third-party certificate. An application treating getCertificationBy(...).isValid() or getDelegationBy(...) as an identity or trusted-introducer decision would attribute the attacker's assertion to the offline primary key. The same held for a legacy RSA subkey bound only for encryption, whose algorithm is nonetheless able to sign. This does not forge the primary key's signature or recover any private key; it promotes an already-compromised restricted subkey to the primary key's identity-issuing authority, defeating the containment the key-flag separation provides. A third-party certification or delegation is now attributed to the issuing certificate only when the component key that made it is the primary key, or is a subkey holding CERTIFY_OTHER when the signature was created, so certification-capable subkeys continue to be accepted; primary keys are accepted whatever their key flags say, since a primary key is certification-capable by construction and certificates carrying no key flags subpacket at all are common. Third-party revocations are deliberately outside the rule, since declining to honour one would keep trust alive rather than withdraw it.",
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"supportingMedia": [
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{
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"type": "text/html",
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"base64": false,
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"value": "<p>In Bouncy Castle for Java before 1.86, the high-level OpenPGP certificate API accepted a third-party certification or trust delegation from any component key of the issuing certificate, without requiring that component to have been granted the authority to certify. OpenPGPCertificate.getCertificationBy() and getDelegationBy() resolve a third-party signature by matching its issuer key identifier against every key of the third-party certificate, then verify the issuing component's binding chain and the signature itself; nothing checked that the issuing component carried the RFC 9580 sec. 5.2.3.29 certification key flag (CERTIFY_OTHER) when the signature was created. A subkey bound only with SIGN_DATA - the online signing subkey of exactly the offline-primary arrangement those key flags exist to express - could therefore issue a positive User ID certification over an attacker-controlled identity, or a full-trust depth-one direct-key delegation of introducer trust, and the API returned it as a valid signature chain attributed to the third-party certificate. An application treating getCertificationBy(...).isValid() or getDelegationBy(...) as an identity or trusted-introducer decision would attribute the attacker's assertion to the offline primary key. The same held for a legacy RSA subkey bound only for encryption, whose algorithm is nonetheless able to sign. This does not forge the primary key's signature or recover any private key; it promotes an already-compromised restricted subkey to the primary key's identity-issuing authority, defeating the containment the key-flag separation provides. A third-party certification or delegation is now attributed to the issuing certificate only when the component key that made it is the primary key, or is a subkey holding CERTIFY_OTHER when the signature was created, so certification-capable subkeys continue to be accepted; primary keys are accepted whatever their key flags say, since a primary key is certification-capable by construction and certificates carrying no key flags subpacket at all are common. Third-party revocations are deliberately outside the rule, since declining to honour one would keep trust alive rather than withdraw it.</p>"
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}
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]
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}
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],
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"references": [
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{
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"url": "https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9071886",
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"tags": [
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"vendor-advisory"
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]
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},
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{
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"url": "https://github.com/bcgit/bc-java/commit/f0d5c8535aeff3f34b7b6b6289ee78c2ea36a3fb",
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"tags": [
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"patch"
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]
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}
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],
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"metrics": [
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{
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"format": "CVSS",
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"scenarios": [
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{
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"lang": "en",
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"value": "GENERAL"
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}
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],
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"cvssV4_0": {
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"attackVector": "NETWORK",
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"attackComplexity": "LOW",
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"attackRequirements": "PRESENT",
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"privilegesRequired": "NONE",
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"userInteraction": "NONE",
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"vulnConfidentialityImpact": "NONE",
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"subConfidentialityImpact": "NONE",
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"vulnIntegrityImpact": "HIGH",
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"subIntegrityImpact": "NONE",
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"vulnAvailabilityImpact": "NONE",
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"subAvailabilityImpact": "NONE",
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"exploitMaturity": "NOT_DEFINED",
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"Safety": "NOT_DEFINED",
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"Automatable": "NOT_DEFINED",
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"Recovery": "NOT_DEFINED",
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"valueDensity": "NOT_DEFINED",
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"vulnerabilityResponseEffort": "NOT_DEFINED",
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"providerUrgency": "AMBER",
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"version": "4.0",
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"baseSeverity": "HIGH",
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"baseScore": 8.2,
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"vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/U:Amber"
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}
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}
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],
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"credits": [
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{
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"lang": "en",
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"value": "Bhargava Shastry",
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"type": "reporter"
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}
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],
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"source": {
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"discovery": "EXTERNAL"
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},
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"x_generator": {
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"engine": "bc release-notes template"
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}
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},
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"adp": [
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{
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"metrics": [
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{
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"other": {
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"type": "ssvc",
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"content": {
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"timestamp": "2026-10-05T16:02:59.243532Z",
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"id": "CVE-2026-71886",
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"options": [
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{
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"Exploitation": "none"
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},
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{
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"Automatable": "no"
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},
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{
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"Technical Impact": "partial"
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}
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],
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"role": "CISA Coordinator",
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"version": "2.0.3"
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}
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}
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}
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],
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"title": "CISA ADP Vulnrichment",
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"providerMetadata": {
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"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"shortName": "CISA-ADP",
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"dateUpdated": "2026-10-05T16:03:23.403Z"
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}
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}
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]
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}
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} |