diff --git a/package.json b/package.json
index f5cac36..4f786ef 100644
--- a/package.json
+++ b/package.json
@@ -54,7 +54,7 @@
     "jimp": "^0.9.3",
     "jquery": "^3.3.1",
     "kcors": "^2.2.2",
-    "koa": "^2.7.0",
+    "koa": "^2.11.0",
     "koa-bodyparser": "^4.2.1",
     "koa-compress": "~3.0.0",
     "koa-csrf": "^3.0.7",
diff --git a/yarn.lock b/yarn.lock
index 5f5f3e8..d212b02 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2100,13 +2100,13 @@ cookiejar@^2.1.0:
   resolved "https://registry.yarnpkg.com/cookiejar/-/cookiejar-2.1.2.tgz#dd8a235530752f988f9a0844f3fc589e3111125c"
   integrity sha512-Mw+adcfzPxcPeI+0WlvRrr/3lGVO0bD75SxX6811cxSh1Wbxx7xZBGK1eVtDf6si8rg2lhnUjsVLMFMfbRIuwA==
 
-cookies@~0.7.1:
-  version "0.7.3"
-  resolved "https://registry.yarnpkg.com/cookies/-/cookies-0.7.3.tgz#7912ce21fbf2e8c2da70cf1c3f351aecf59dadfa"
-  integrity sha512-+gixgxYSgQLTaTIilDHAdlNPZDENDQernEMiIcZpYYP14zgHsCt4Ce1FEjFtcp6GefhozebB6orvhAAWx/IS0A==
+cookies@~0.8.0:
+  version "0.8.0"
+  resolved "https://registry.yarnpkg.com/cookies/-/cookies-0.8.0.tgz#1293ce4b391740a8406e3c9870e828c4b54f3f90"
+  integrity sha512-8aPsApQfebXnuI+537McwYsDtjVxGm8gTIzQI3FDW6t5t/DAhERxtnbEPN/8RX+uZthoz4eCOgloXaE5cYyNow==
   dependencies:
-    depd "~1.1.2"
-    keygrip "~1.0.3"
+    depd "~2.0.0"
+    keygrip "~1.1.0"
 
 copy-concurrently@^1.0.0:
   version "1.0.5"
@@ -2423,7 +2423,7 @@ denque@^1.1.0:
   resolved "https://registry.yarnpkg.com/denque/-/denque-1.4.1.tgz#6744ff7641c148c3f8a69c307e51235c1f4a37cf"
   integrity sha512-OfzPuSZKGcgr96rf1oODnfjqBFmr1DVoc/TrItj3Ohe0Ah1C5WX5Baquw/9U9KovnQ88EqmJbD66rKYUQYN1tQ==
 
-depd@2.0.0:
+depd@2.0.0, depd@~2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/depd/-/depd-2.0.0.tgz#b696163cc757560d09cf22cc8fad1571b79e76df"
   integrity sha512-g7nH6P6dyDioJogAAGprGpCtVImJhpPk/roCzdb3fIh61/s/nPsfR6onyMwkCAR/OlC3yBC0lESvUoQEAssIrw==
@@ -2619,7 +2619,7 @@ emojis-list@^2.0.0:
   resolved "https://registry.yarnpkg.com/emojis-list/-/emojis-list-2.1.0.tgz#4daa4d9db00f9819880c79fa457ae5b09a1fd389"
   integrity sha1-TapNnbAPmBmIDHn6RXrlsJof04k=
 
-encodeurl@~1.0.2:
+encodeurl@^1.0.2, encodeurl@~1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/encodeurl/-/encodeurl-1.0.2.tgz#ad3ff4c86ec2d029322f5a02c3a9a606c95b3f59"
   integrity sha1-rT/0yG7C0CkyL1oCw6mmBslbP1k=
@@ -4593,10 +4593,12 @@ kcors@^2.2.2:
   resolved "https://registry.yarnpkg.com/kcors/-/kcors-2.2.2.tgz#b6250e7a4f0a33c8f477b7fd0dfa11a3f3ca518d"
   integrity sha512-rIqbKa2S0gT0wC/790jsQM6hNpABHBNWQ7+XYS1xJV6zOGxlanW+RtCmlDn6wPZsGpRk371yy8abfBgl2OTavg==
 
-keygrip@~1.0.3:
-  version "1.0.3"
-  resolved "https://registry.yarnpkg.com/keygrip/-/keygrip-1.0.3.tgz#399d709f0aed2bab0a059e0cdd3a5023a053e1dc"
-  integrity sha512-/PpesirAIfaklxUzp4Yb7xBper9MwP6hNRA6BGGUFCgbJ+BM5CKBtsoxinNXkLHAr+GXS1/lSlF2rP7cv5Fl+g==
+keygrip@~1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/keygrip/-/keygrip-1.1.0.tgz#871b1681d5e159c62a445b0c74b615e0917e7226"
+  integrity sha512-iYSchDJ+liQ8iwbSI2QqsQOvqv58eJCEanyJPJi+Khyu8smkcKSFUCbPwzFcL7YVtZ6eONjqRX/38caJ7QjRAQ==
+  dependencies:
+    tsscmp "1.0.6"
 
 kind-of@^3.0.2, kind-of@^3.0.3, kind-of@^3.2.0:
   version "3.2.2"
@@ -4788,20 +4790,21 @@ koa-websocket@^5.0.1:
     koa-compose "^4.0.0"
     ws "^5.2.0"
 
-koa@^2.7.0:
-  version "2.7.0"
-  resolved "https://registry.yarnpkg.com/koa/-/koa-2.7.0.tgz#7e00843506942b9d82c6cc33749f657c6e5e7adf"
-  integrity sha512-7ojD05s2Q+hFudF8tDLZ1CpCdVZw8JQELWSkcfG9bdtoTDzMmkRF6BQBU7JzIzCCOY3xd3tftiy/loHBUYaY2Q==
+koa@^2.11.0:
+  version "2.11.0"
+  resolved "https://registry.yarnpkg.com/koa/-/koa-2.11.0.tgz#fe5a51c46f566d27632dd5dc8fd5d7dd44f935a4"
+  integrity sha512-EpR9dElBTDlaDgyhDMiLkXrPwp6ZqgAIBvhhmxQ9XN4TFgW+gEz6tkcsNI6BnUbUftrKDjVFj4lW2/J2aNBMMA==
   dependencies:
     accepts "^1.3.5"
     cache-content-type "^1.0.0"
     content-disposition "~0.5.2"
     content-type "^1.0.4"
-    cookies "~0.7.1"
+    cookies "~0.8.0"
     debug "~3.1.0"
     delegates "^1.0.0"
     depd "^1.1.2"
     destroy "^1.0.4"
+    encodeurl "^1.0.2"
     error-inject "^1.0.0"
     escape-html "^1.0.3"
     fresh "~0.5.2"
@@ -4810,7 +4813,6 @@ koa@^2.7.0:
     is-generator-function "^1.0.7"
     koa-compose "^4.1.0"
     koa-convert "^1.2.0"
-    koa-is-json "^1.0.0"
     on-finished "^2.3.0"
     only "~0.0.2"
     parseurl "^1.3.2"