Company

Gakken Inc.

Gakken Inc. (Shinagawa, Tokyo; Information and communications) appears in 2 related cybersecurity incidents. 1 was a precautionary service shutdown. The latest was disclosed on 2026-10-21.

Profile

Industry/type: Information and communications
Location: Tokyo, Shinagawa
Website: https://www.corp-gakken.co.jp/

Public figures

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Metric	Value		As of	Source
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Incident history

Disclosed 2026-10-21Updated 2026-10-27 09:05Aichi, Akita, Aomori, Chiba, Ehime, Fukui, Fukuoka, Fukushima, Gifu, Gunma, Hiroshima, Hokkaido, Hyogo, Ibaraki, Ishikawa, Iwate, Kagawa, Kagoshima, Kanagawa, Kochi, Kumamoto, Kyoto, Mie, Miyagi, Miyazaki, Nagano, Nagasaki, Nara, Niigata, Oita, Okayama, Okinawa, Osaka, Saga, Saitama, Shiga, Shimane, Shizuoka, Tochigi, Tokushima, Tokyo, Tottori, Toyama, Wakayama, Yamagata, Yamaguchi, Yamanashi[Ongoing][Severity: Moderate][Precautionary halt][Minor]
php2shell: critical flaws in PHP
[Web app exploit][Service outage]Organizations 608
Disclosed 2026-10-08Updated 2026-10-26 18:25Tokyo[Contained][Severity: Moderate][Through a supplier][Moderate]
Gakken: group sites down after unauthorized access to an external server
[Intrusion][Service outage]Organizations 3

		Incident	Role	Impact level				Methods	Impacts		Status
2026-10-21	2026-10-27 09:05	php2shell: critical flaws in PHP	[Precautionary halt]	[Minor]	[Moderate]	608 Hiroshima Prefecture, Ibaraki Prefectural Police, Iwate Prefecture, NTT DOCOMO, Inc., SoftBank Corp., Aomori Michinoku Bank, Ltd., Itabashi City, Kasukabe City, Kokubunji City, LIFULL Co., Ltd., Marugame City, Matsue City, Musashino City, Odawara City, Saga Prefecture, Saijo City, Sanda City, The Shizuoka Bank, Ltd., Tottori Prefecture, The Akita Bank, Ltd., Akita-ken Credit Cooperative, The Bank of Toyama, Ltd., Every Inc., Fukuoka Hibiki Shinkin Bank, Future Shop Co., Ltd., Hanamaki City, Hekikai Shinkin Bank, The Hokkaido Bank, Ltd., Ibaraki-ken Credit Cooperative, Isehara City, Kagawa-ken Credit Cooperative, Mishima Shinkin Bank, Osaka Prefectural Hospital Organization, Satsumasendai City, Tenri City, Tomato Bank, Ltd., Toyooka City, Yamanashi Kenmin Credit Cooperative, Consumer Affairs Agency, Imperial Household Agency, Japan Meteorological Agency, Ministry of Education, Culture, Sports, Science and Technology, Ministry of Finance, Ministry of Health, Labour and Welfare, Ministry of Land, Infrastructure, Transport and Tourism, National Tax Agency, Supreme Court of Japan, Tokyo Metropolitan Government, Aichi Prefecture, Aomori Prefectural Government, Asahi Group Holdings, Ltd., Central Japan Railway Company, Chiba Prefectural Government, City of Sendai, City of Yokohama, Daiwa Securities Co., Ltd., East Japan Railway Company, Ehime Prefecture, Fukuoka City, Fukuoka Prefecture, Fukushima Prefecture, Gifu Prefectural Police, Gifu Prefecture, Hyogo Prefecture, Ibaraki Prefectural Government, Institute of Science Tokyo, Ishikawa Prefectural Police, Ishikawa Prefecture, Japan Airlines Co., Ltd., Kagoshima Prefecture, Kanagawa Prefectural Police, Kanagawa Prefecture, Kawasaki City, Kumamoto Prefecture, Kyoto City, Kyushu Railway Company, Mie Prefectural Government, Mie Prefectural Police, Miyagi Prefecture, Miyazaki Prefecture, Mizuho Bank, Ltd., MUFG Bank, Ltd., Nagano Prefectural Government, Nagasaki Prefecture, Nagoya City, Nara Prefecture, Niigata Prefecture, NTT DOCOMO Business, Inc., Oita Prefectural Government, Okayama Prefecture, Okinawa Prefectural Government, Osaka City, Osaka Prefectural Government, Saitama City, Sapporo City, Shiga Prefecture, Shizuoka Prefecture, Suzuki Motor Corporation, Tochigi Prefecture, Tokio Marine & Nichido Fire Insurance Co., Ltd., West Japan Railway Company, Yamaguchi Prefecture, Yamaha Motor Co., Ltd., The 77 Bank, Ltd., Abiko City, Ageo City, Aizuwakamatsu City, Akashi City, Akita Prefecture, Amagasaki City, Anjo City, Aomori City, Asaka City, The Awa Bank, Ltd., Bandai Namco Experience Inc., Bunkyo City, Chiba City, Chigasaki City, Chikushino City, Chofu City, The Chugoku Bank, Limited, Chuo City, City of Shizuoka, Daito City, Dwango Co., Ltd., Ebetsu City, Edogawa City, Ezaki Glico Co., Ltd., Fuchu City, Fujieda City, Fujimino City, Fujisawa City, Fukaya City, Fukui City, Fukui Prefecture, Fukushima City, Fukuyama City, Funabashi City, Gifu City, H.I.S. Co., Ltd., Habikino City, Hachinohe City, Hakusan City, Hamamatsu City, Handa City, Hankyu Corporation, Higashihiroshima City, Higashiomi City, Higashiosaka City, Hikone City, Himeji City, Hino City, Hiratsuka City, Hitachi City, Hitachinaka City, The Hokkoku Bank, Ltd., Ibaraki City, Ichibanya Co., Ltd., Ichikawa City, Ichinomiya City, Ikeda City, Ikoma City, Imabari City, Inazawa City, Inzai City, Iruma City, Isahaya City, Isesaki City, Iwata City, Izumi City, Izumi Co., Ltd., Izumo City, Kadoma City, Kagawa Prefecture, The Kagoshima Bank, Ltd., Kagoshima City, Kakamigahara City, Kakogawa City, Kanazawa City, Karatsu City, Kariya City, Kashihara City, Kashiwa City, Kasuga City, Kasugai City, Kawagoe City, Kawaguchi City, Kawanishi City, Kisarazu City, Kishiwada City, Kita City, Kitakyushu City, Kofu City, Koga City, Koike-ya Inc., Komaki City, Komatsu City, Konosu City, Koriyama City, Koshigaya City, Koto City, Kumagaya City, Kumamoto City, Kure City, Kusatsu City, Kushiro City, Kuwana City, Kyushu Electric Power Company, Incorporated, Matsubara City, Matsudo City, Matsumoto City, Matsusaka City, Matsuyama City, Medley, Inc., Meguro City, Minato City, Minoh City, Misato City, Mitaka City, Mito City, Miyakonojo City, Miyazaki City, Moriguchi City, Morioka City, Nagahama City, Nagano City, Nagaoka City, Nagareyama City, Nagasaki City, Naha City, Nara City, Narashino City, Nasushiobara City, Nerima City, Niigata City, Niihama City, Niiza City, Nishinomiya City, Nobeoka City, Noda City, Obihiro City, Ogaki City, Oita City, Okayama City, Okazaki City, Okinawa City, Onojo City, Onomichi City, Oshu City, Otaru City, Otsu City, Oyama City, Saga City, Saga Prefectural Police, Sagamihara City, Sakura City, Sakura internet Inc., The San-in Godo Bank, Ltd., Sayama City, SEGA FAVE Corporation, Setagaya City, Shimane Prefecture, Shimonoseki City, Shinjuku City, Soka City, Suginami City, Suita City, Suzuka City, The Taiko Bank, Ltd., Takamatsu City, Takaoka City, Takatsuki City, Tama City, Toda City, Tokorozawa City, Tokushima City, Tokushima Prefectural Government, Toshima City, Tottori City, Toyama City, Toyama Prefectural Government, Toyohashi City, Toyokawa City, Toyonaka City, Toyota City, Tsukuba City, Tsuruoka City, Ube City, Uji City, Uruma City, Utsunomiya City, Wakayama Prefecture, Yachiyo City, Yaizu City, Yamagata City, Yamagata Prefectural Government, Yamaha Corporation, The Yamanashi Chuo Bank, Ltd., Yamanashi Prefecture, Yamato City, Yao City, Yokkaichi City, Yokosuka City, Yonago City, Zama City, Zensho Holdings Co., Ltd., Aichi Bank, Ltd., Aichi Shinkin Bank, AIRDO Co., Ltd., Akita University, All Nippon Airways Co., Ltd., Anan City, Aoimori Shinkin Bank, Aoyama Gakuin, Aozora Bank, Ltd., Arc System Works Co., Ltd., The Ashikaga Bank, Ltd., Ashikaga University, asken Inc., au Jibun Bank Corporation, Audio-Technica Corporation, Avispa Fukuoka Inc., Ayase City, Bandai Namco Amusement Inc., Bandai Namco Entertainment Inc., Bandai Namco Filmworks Inc., The Bank of Fukuoka, Ltd., The Bank of Iwate, Ltd., The Bank of Kochi, Ltd., The Bank of Kyoto, Ltd., The Bank of Nagoya, Ltd., The Bank of Saga Ltd., Bank of the Ryukyus, Limited, The Bank of Yokohama, Ltd., BASE, Inc., Belc Co., Ltd., Buffalo Inc., Bushiroad Creative Inc., The Chiba Bank, Ltd., The Chiba Kogyo Bank, Ltd., Chiba University, Chikusei City, Chita City, Chitose City, Chiyoda City, Chubu University, CoDMON, Inc., Cosmos Pharmaceutical Corporation, Creema Ltd., Cygames, Inc., Daimaru Matsuzakaya Department Stores Co., Ltd., Daishi Hokuetsu Bank, Ltd., Daiwa Connect Securities Co., Ltd., densai.net Co., Ltd., Digital Hollywood Co., Ltd., DMM.com LLC, Dokkyo Gakuen, e-learning Co., Ltd., East Nippon Expressway Company, Limited, The Ehime Bank, Ltd., Ehime University, The Energy Conservation Center, Japan, Enshu Railway Co., Ltd., F.M.Tochigi Broadcasting Co., Ltd., The First Bank of Toyama, Ltd., The Fukui Bank, Ltd., Fukui Shinkin Bank, Fukuoka Broadcasting System Corporation, The Fukuoka Chuo Bank, Ltd., Fukuoka International Airport Co., Ltd., Fukuoka SoftBank Hawks Corp., Fukushima Television Inc., Fukutsu City, Funada Educational Foundation, Fussa City, Gakken Inc., Genki Global Dining Concepts Corporation, GMO Pepabo, Inc., GRIFFY Inc., The Gunma Bank, Ltd., Gyoda City, Hachijuni Nagano Bank, Ltd., Hamamatsu University School of Medicine, Hanno City, Hanshin Electric Railway Co., Ltd., Hanshin Tigers Baseball Club, Ltd., Hashimoto City, Hidaka City, The Higashi-Nippon Bank, Limited, The Higo Bank, Ltd., Hirosaki University, The Hiroshima Bank, Ltd., Hiroshima Electric Railway Co., Ltd., Hiroshima Television Corporation, Hiroshima University, The Hokkaido Shimbun Press Inc., The Hokuriku Bank, Ltd., Hokuriku Railroad Co., Ltd., Hokuto Bank Inc., Honjo City, The Howa Bank, Ltd., Hozawa Gakuen, The Hyakugo Bank, Ltd., The Hyakujushi Bank, Ltd., I-O Data, Inc., IDC Frontier Inc., INEST, Inc., Inter Action Corporation, Inuyama City, Ishikari City, Iwamizawa City, The Iwate Nippo Co., Ltd., The Iyo Bank, Ltd., Izumi City, Izumisano City, Japan Agency for Local Authority Information Systems, Japan Medical Association, Japan Patent Information Organization, Japanese Association of Certified Social Workers, The Joyo Bank, Ltd., JR Bus Chugoku Company, Jubilo Co., Ltd., The Juhachi-Shinwa Bank, Ltd., The Juroku Bank, Ltd., Kaga City, Kagawa University, Kagoya Japan Inc., Kaizuka City, Kameoka City, Kanazawa College of Art, Kanazawa University, Kashiba City, Kashima City, Kawachinagano City, Kawai Musical Instruments Manufacturing Co., Ltd., KDDI Web Communications Inc., Keihan Holdings Co., Ltd., Keikyu Corporation, Keio University, The Keiyo Bank, Ltd., Kimitsu City, Kiryu City, Kitakami City, Kizugawa City, Kochi Broadcasting Co., Ltd., Kochi Shimbun Inc., Koga City, Koka City, Kokopelli Inc., Konan City, Konan City, Kosai City, KSB Setonaikai Broadcasting Inc., kubell Co., Ltd., The Kumamoto Bank, Ltd., Kumamoto Telecasting Corporation, Kumamoto University, Kunitachi City, Kyoto Prefectural Public University Corporation, Kyuden Holdings Inc., Kyushu Electric Power Transmission and Distribution Co., Inc., Kyushu Institute of Technology, Maizuru City, Marugame Seimen Co., Ltd., Maruhiro Department Store Inc., Mathematics Certification Institute of Japan, Maxvalu Tokai Co., Ltd., Meijo University, Metropolitan Intercity Railway Company, Miki City, The Minami-Nippon Bank, Ltd., Mito Shinkin Bank, Mitsubishi UFJ Morgan Stanley Securities Co., Ltd., The Miyazaki Taiyo Bank, Ltd., Mizuho Securities Co., Ltd., Mobara City, Moneytree K.K., Moriyama City, Muko City, The Musashino Bank, Ltd., Nagaokakyo City, Nagoya Gakuin University, Nagoya Institute of Technology, Nagoya Railroad Co., Ltd., Nagoya Stock Exchange, Inc., Nagoya University, Nankai Co., Ltd., National Federation of Prefectural Kyosai Cooperatives, National University Corporation Hokkaido Higher Education and Research System, ND Software Co., Ltd., NIFTY Corporation, Nikko City, Nippon Life Insurance Company, The Nishi-Nippon City Bank, Ltd., Nishi-Nippon Railroad Co., Ltd., Nisshin City, Nitroplus Inc., Nogata City, Nojima Corporation, North Pacific Bank, Ltd., NSD Co., Ltd., Obu City, Odakyu Electric Railway Co., Ltd., The Ogaki Kyoritsu Bank, Ltd., Ogori City, The Oita Bank, Ltd., Okinawa Prefectural University of Arts, Omihachiman City, OMRON Healthcare Co., Ltd., Ootoya Holdings Co., Ltd., Osaka Fumin Kyosai Cooperative, Osaka Gakuin University, Osaka Metro Co., Ltd., Otemon Gakuin, Owariasahi City, Phiten Co., Ltd., PhotoCreate Co., Ltd., pixiv Inc., Premium Group Co., Ltd., Radio Fukushima Inc., Rakuten Group, Inc., Resona Bank, Limited, Ritto City, Ryukoku University, The Saga Kyoei Bank, Ltd., The Saikyo Bank, Ltd., Sakura Saku Mirai Inc., Sakurai City, San ju San Bank, Ltd., Satudora Holdings Co., Ltd., SBI Shinsei Bank, Limited, SEGA Corporation, Seinan Gakuin, Seirei Social Welfare Community, The Sendai Bank Ltd., Sendai International Airport Co., Ltd., Sennan City, Senshu Ikeda Tokai Tokyo Securities Co., Ltd., Senshu University, Settsu City, Shibaura Institute of Technology, The Shiga Bank, Ltd., Shiga University of Medical Science, Shiki City, The Shikoku Bank, Ltd., Shikoku Electric Power Co., Inc., Shikoku Gas Co., Ltd., Shikoku Railway Company, Shimonoseki City University, Shiroi City, Shizuoka University, The Shonai Bank, Ltd., Skymark Airlines Inc., Sodegaura City, Sogo & Seibu Co., Ltd., Soja City, Sony Marketing Inc., SpiderPlus & Co., Star Flyer Inc., Studio Inc., Tahara City, Takaishi City, Takayama City, Tamba City, Tane-Yaku Jetfoil Inc., TKC Corporation, The To-o Nippo Press Co., Ltd., Tobu Store Co., Ltd., The Tochigi Bank, Ltd., Tochigi Broadcasting Inc., Tochigi Television Inc., The Toho Bank, Ltd., Tohoku Electric Power Co., Inc., Tohoku Electric Power Network Co., Inc., TOKAI Communications Corporation, Tokai National Higher Education and Research System, Toki City, Tokio Marine & Nichido Life Insurance Co., Ltd., Tokoname City, Tokushima University, Tokyo University of Foreign Studies, Tokyo University of Pharmacy and Life Sciences, Tono Shinkin Bank, Tosu City, Tottori University, Toyo University, Tribeck Inc., Tsukuba Bank, Ltd., Tsumura & Co., Tsuyama City, Umemura Gakuen, University of Electro-Communications, University of the Ryukyus, Uryuyama Gakuen, Wako City, XServer Inc., Yachimata City, The Yamagata Bank, Ltd., Yamagata Shimbun Inc., Yamatokoriyama City, Yamazawa Co., Ltd., Yasu City, Yokohama City University, Yokohama Shinkin Bank, Yonezawa City, Yotsukaido City, Yukuhashi City, Yurihonjo City	Aichi, Akita, Aomori, Chiba, Ehime, Fukui, Fukuoka, Fukushima, Gifu, Gunma, Hiroshima, Hokkaido, Hyogo, Ibaraki, Ishikawa, Iwate, Kagawa, Kagoshima, Kanagawa, Kochi, Kumamoto, Kyoto, Mie, Miyagi, Miyazaki, Nagano, Nagasaki, Nara, Niigata, Oita, Okayama, Okinawa, Osaka, Saga, Saitama, Shiga, Shimane, Shizuoka, Tochigi, Tokushima, Tokyo, Tottori, Toyama, Wakayama, Yamagata, Yamaguchi, Yamanashi	[Web app exploit]	[Service outage]	Unknown	[Ongoing]
2026-10-08	2026-10-26 18:25	Gakken: group sites down after unauthorized access to an external server	[Through a supplier]	[Moderate]	[Moderate]	3 Gakken Educational Co., Ltd., Gakken Inc., Gakken Medical Support Co., Ltd.	Tokyo	[Intrusion]	[Service outage]	Unknown	[Contained]