{"id":"CURL-CVE-2021-22898","summary":"TELNET stack contents disclosure","details":"curl supports the `-t` command line option, known as `CURLOPT_TELNETOPTIONS`\nin libcurl. This rarely used option is used to send variable=content pairs to\nTELNET servers.\n\nDue to flaw in the option parser for sending `NEW_ENV` variables, libcurl\ncould be made to pass on uninitialized data from a stack based buffer to the\nserver. Therefore potentially revealing sensitive internal information to the\nserver using a clear-text network protocol.\n\nThis could happen because curl did not check the return code from a\n`sscanf(command, \"%127[^,],%127s\")` function invoke correctly, and would leave\nthe piece of the send buffer uninitialized for the value part if it was\nprovided longer than 127 bytes. The buffer used for this is 2048 bytes big and\nthe *variable* part of the *variable=content* pairs would be stored correctly\nin the send buffer, making curl sending \"interleaved\" bytes sequences of stack\ncontents. A single curl TELNET handshake could then be made to send off a\ntotal of around 1800 bytes of (non-contiguous) stack contents in this style:\n\n    [control byte]name[control byte]\n    stack contents\n    [control byte]name[control byte]\n    stack contents\n    ...\n\nAn easy proof of concept command line looks like this:\n\n    curl telnet://example.com -tNEW_ENV=a,bbbbbb (256 'b's)","aliases":["CVE-2021-22898"],"modified":"2024-01-25T02:42:49.602163Z","published":"2021-05-26T08:00:00Z","database_specific":{"issue":"https://hackerone.com/reports/1176461","www":"https://curl.se/docs/CVE-2021-22898.html","award":{"amount":"1000","currency":"USD"},"severity":"Medium","URL":"https://curl.se/docs/CVE-2021-22898.json","CWE":{"desc":"Use of Uninitialized Variable","id":"CWE-457"},"affects":"both","package":"curl","last_affected":"7.76.1"},"affected":[{"ranges":[{"type":"SEMVER","events":[{"introduced":"7.7"},{"fixed":"7.77.0"}]},{"type":"GIT","repo":"https://github.com/curl/curl.git","events":[{"introduced":"a1d6ad26100bc493c7b04f1301b1634b7f5aa8b4"},{"fixed":"39ce47f219b09c380b81f89fe54ac586c8db6bde"}]}],"versions":["7.76.1","7.76.0","7.75.0","7.74.0","7.73.0","7.72.0","7.71.1","7.71.0","7.70.0","7.69.1","7.69.0","7.68.0","7.67.0","7.66.0","7.65.3","7.65.2","7.65.1","7.65.0","7.64.1","7.64.0","7.63.0","7.62.0","7.61.1","7.61.0","7.60.0","7.59.0","7.58.0","7.57.0","7.56.1","7.56.0","7.55.1","7.55.0","7.54.1","7.54.0","7.53.1","7.53.0","7.52.1","7.52.0","7.51.0","7.50.3","7.50.2","7.50.1","7.50.0","7.49.1","7.49.0","7.48.0","7.47.1","7.47.0","7.46.0","7.45.0","7.44.0","7.43.0","7.42.1","7.42.0","7.41.0","7.40.0","7.39.0","7.38.0","7.37.1","7.37.0","7.36.0","7.35.0","7.34.0","7.33.0","7.32.0","7.31.0","7.30.0","7.29.0","7.28.1","7.28.0","7.27.0","7.26.0","7.25.0","7.24.0","7.23.1","7.23.0","7.22.0","7.21.7","7.21.6","7.21.5","7.21.4","7.21.3","7.21.2","7.21.1","7.21.0","7.20.1","7.20.0","7.19.7","7.19.6","7.19.5","7.19.4","7.19.3","7.19.2","7.19.1","7.19.0","7.18.2","7.18.1","7.18.0","7.17.1","7.17.0","7.16.4","7.16.3","7.16.2","7.16.1","7.16.0","7.15.5","7.15.4","7.15.3","7.15.2","7.15.1","7.15.0","7.14.1","7.14.0","7.13.2","7.13.1","7.13.0","7.12.3","7.12.2","7.12.1","7.12.0","7.11.2","7.11.1","7.11.0","7.10.8","7.10.7","7.10.6","7.10.5","7.10.4","7.10.3","7.10.2","7.10.1","7.10","7.9.8","7.9.7","7.9.6","7.9.5","7.9.4","7.9.3","7.9.2","7.9.1","7.9","7.8.1","7.8","7.7.3","7.7.2","7.7.1","7.7"],"database_specific":{"vanir_signatures":[{"source":"https://github.com/curl/curl.git/commit/39ce47f219b09c380b81f89fe54ac586c8db6bde","signature_version":"v1","target":{"file":"lib/telnet.c","function":"suboption"},"signature_type":"Function","digest":{"length":2157,"function_hash":"278374588349917216130301655130053651655"},"deprecated":false,"id":"CURL-CVE-2021-22898-40e715cc"},{"source":"https://github.com/curl/curl.git/commit/39ce47f219b09c380b81f89fe54ac586c8db6bde","signature_version":"v1","target":{"file":"lib/telnet.c"},"signature_type":"Line","digest":{"threshold":0.9,"line_hashes":["61856253574400304251431398167931381325","240827579168948696521027871241596897491","110949695118154885913644981527849872064","233170882117233154983717156358912138949"]},"deprecated":false,"id":"CURL-CVE-2021-22898-c1f30bcf"}],"source":"https://curl.se/docs/CURL-CVE-2021-22898.json"}}],"schema_version":"1.7.3","credits":[{"name":"Harry Sintonen","type":"FINDER"},{"name":"Harry Sintonen","type":"REMEDIATION_DEVELOPER"}]}