diff --git a/server/src/routes/oauth-social.js b/server/src/routes/oauth-social.js
index 9c09a34..5e6137e 100644
--- a/server/src/routes/oauth-social.js
+++ b/server/src/routes/oauth-social.js
@@ -3,6 +3,21 @@ import { normalizeEmail } from '../lib/auth.js'
 import { generateAvatar } from '../lib/generate-avatar.js'
 import { prisma } from '../lib/prisma.js'
 
+const pkceStore = new Map()
+
+function storePkce(state, codeVerifier, meta = {}) {
+  pkceStore.set(state, { codeVerifier, meta, createdAt: Date.now() })
+}
+
+function consumePkce(state) {
+  const entry = pkceStore.get(state)
+  if (entry) {
+    pkceStore.delete(state)
+    return { codeVerifier: entry.codeVerifier, meta: entry.meta }
+  }
+  return null
+}
+
 function generatePkcePair() {
   const verifier = crypto.randomBytes(48).toString('base64url').slice(0, 64)
   const challenge = crypto.createHash('sha256').update(verifier).digest('base64url')
@@ -99,7 +114,8 @@ export async function registerOAuthSocialRoutes(fastify) {
 
     const redirectUri = `${serverPublic}/api/auth/oauth/vk/callback`
     const { codeVerifier, codeChallenge } = generatePkcePair()
-    const state = fastify.jwt.sign({ oauth: 'vk', cv: codeVerifier }, { expiresIn: '15m' })
+    const state = crypto.randomUUID()
+    storePkce(state, codeVerifier)
 
     const url = new URL('https://id.vk.ru/authorize')
     url.searchParams.set('client_id', clientId)
@@ -125,10 +141,8 @@ export async function registerOAuthSocialRoutes(fastify) {
 
     const redirectUri = `${serverPublic}/api/auth/oauth/vk/callback`
     const { codeVerifier, codeChallenge } = generatePkcePair()
-    const state = fastify.jwt.sign(
-      { oauth: 'vk', action: 'link', userId: request.user.sub, cv: codeVerifier },
-      { expiresIn: '15m' },
-    )
+    const state = crypto.randomUUID()
+    storePkce(state, codeVerifier, { action: 'link', userId: request.user.sub })
 
     const url = new URL('https://id.vk.ru/authorize')
     url.searchParams.set('client_id', clientId)
@@ -148,15 +162,11 @@ export async function registerOAuthSocialRoutes(fastify) {
       return oauthErrorRedirect(reply, String(query.error_description || query.error || 'ошибка VK'))
     }
 
-    const statePayload = (() => {
-      try {
-        const raw = typeof query.state === 'string' ? query.state : ''
-        return fastify.jwt.verify(raw || '')
-      } catch {
-        return null
-      }
-    })()
-    if (!statePayload) return oauthErrorRedirect(reply, 'Недействительный state OAuth')
+    const state = typeof query.state === 'string' ? query.state.trim() : ''
+    if (!state) return oauthErrorRedirect(reply, 'Недействительный state OAuth')
+
+    const pkceEntry = consumePkce(state)
+    if (!pkceEntry) return oauthErrorRedirect(reply, 'Недействительный state OAuth')
 
     const code = typeof query.code === 'string' ? query.code.trim() : ''
     if (!code) return oauthErrorRedirect(reply, 'Не получен код от VK')
@@ -166,14 +176,13 @@ export async function registerOAuthSocialRoutes(fastify) {
     const clientId = process.env.VK_CLIENT_ID
     const clientSecret = process.env.VK_CLIENT_SECRET
     const redirectUri = `${serverPublic}/api/auth/oauth/vk/callback`
-    const codeVerifier = typeof statePayload.cv === 'string' ? statePayload.cv : ''
 
     const body = new URLSearchParams()
     body.set('grant_type', 'authorization_code')
     body.set('client_id', clientId)
     body.set('client_secret', clientSecret)
     body.set('code', code)
-    body.set('code_verifier', codeVerifier)
+    body.set('code_verifier', pkceEntry.codeVerifier)
     body.set('redirect_uri', redirectUri)
     if (deviceId) {
       body.set('device_id', deviceId)
@@ -199,7 +208,7 @@ export async function registerOAuthSocialRoutes(fastify) {
     if (!vkUserId) return oauthErrorRedirect(reply, 'no_user_id')
     if (!emailSuggestion) return oauthErrorRedirect(reply, 'no_email')
 
-    const linkToUserId = statePayload?.action === 'link' ? statePayload.userId : undefined
+    const linkToUserId = pkceEntry.meta?.action === 'link' ? pkceEntry.meta.userId : undefined
 
     const user = await findOrCreateUserFromOAuth({
       provider: 'vk',