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fix(csrf): safely validate decoded token table and fields - #14025
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bhuvan-somisetty wants to merge 2 commits into
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In `apisix/plugins/csrf.lua`, `check_csrf_token` decodes the base64 token into JSON without verifying that the result is a table. When a client supplies a token decoding to a JSON primitive (e.g. number, boolean, null), indexing fields like `token_table["random"]` raises an unhandled Lua runtime error (e.g. `attempt to index a number value`), causing a 500 error. This commit verifies `type(token_table) == "table"` and checks that `random`, `expires`, and `sign` have valid types, safely returning `false` on invalid tokens. Signed-off-by: bhuvan-somisetty <somisettybhuvan5@gmail.com>
Baoyuantop
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Oct 15, 2026
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| === TEST 18: csrf token with invalid non-numeric expires | ||
| --- request | ||
| POST /hello | ||
| --- more_headers | ||
| apisix-csrf-token: eyJyYW5kb20iOjAuMSwiZXhwaXJlcyI6ImludmFsaWQiLCJzaWduIjoiYWJjIn0= | ||
| Cookie: apisix-csrf-token=eyJyYW5kb20iOjAuMSwiZXhwaXJlcyI6ImludmFsaWQiLCJzaWduIjoiYWJjIn0= | ||
| --- error_code: 401 | ||
| --- error_log: no expires in token | ||
| --- no_error_log | ||
| attempt to perform arithmetic | ||
| --- response_body | ||
| {"error_msg":"Failed to verify the csrf token signature"} |
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Field guards lack direct test coverage
The tests cover primitive tokens and invalid expires, but not JSON null or invalid random and sign values. Add those cases to exercise every new guard.
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Added tests for null tokens and bad random/sign types. Thanks!
Signed-off-by: bhuvan-somisetty <somisettybhuvan5@gmail.com>
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Description
In
apisix/plugins/csrf.lua,check_csrf_tokendecodes the base64 token into JSON without verifying that the result is a table. When a client supplies a token decoding to a JSON primitive (e.g. number, boolean, null), indexing fields liketoken_table["random"]raises an unhandled Lua runtime error (e.g.attempt to index a number value), causing an HTTP 500 error instead of cleanly rejecting the request.This PR:
type(token_table) == "table"after JSON decoding.random,expires, andsignare present with valid scalar types.t/plugin/csrf.tverifying that non-table JSON tokens and invalid fields are rejected with HTTP 401 without crashing.Which issue(s) this PR fixes:
Fixes #14024
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