{"schema_version":"1.7.5","id":"CURL-CVE-2018-1000120","published":"2018-03-14T08:00:00Z","modified":"2026-05-27T02:29:24.016779Z","aliases":["CVE-2018-1000120","GHSA-674j-7m97-j2p9"],"summary":"FTP path trickery leads to NIL byte out of bounds write","details":"curl can be fooled into writing a zero byte out of bounds.\n\nThis bug can trigger when curl is told to work on an FTP URL, with the setting\nto only issue a single CWD command (`--ftp-method singlecwd` or the libcurl\nalternative `CURLOPT_FTP_FILEMETHOD`).\n\ncurl then URL-decodes the given path, calls strlen() on the result and deducts\nthe length of the filename part to find the end of the directory within the\nbuffer. It then writes a zero byte on that index, in a buffer allocated on the\nheap.\n\nIf the directory part of the URL contains a \"%00\" sequence, the directory\nlength might end up shorter than the filename path, making the calculation\n`size_t index = directory_len - filepart_len` end up with a huge index\nvariable for where the zero byte gets stored: `heap_buffer[index] = 0`. On\nseveral architectures that huge index wraps and works as a negative value,\nthus overwriting memory *before* the intended heap buffer.\n\nBy using different file part lengths and putting %00 in different places in\nthe URL, an attacker that can control what paths a curl-using application uses\ncan write that zero byte on different indexes.","affected":[{"ranges":[{"type":"SEMVER","events":[{"introduced":"7.12.3"},{"fixed":"7.59.0"}]},{"type":"GIT","repo":"https://github.com/curl/curl.git","events":[{"introduced":"6e1e9caa32da099569bb95e64faf0b5f3cf103b5"},{"fixed":"535432c0adb62fe167ec09621500470b6fa4eb0f"}]}],"versions":["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","curl-7_58_0","curl-7_57_0","curl-7_56_1","curl-7_56_0","curl-7_55_1","curl-7_55_0","curl-7_54_1","curl-7_54_0","curl-7_53_1","curl-7_53_0","curl-7_52_1","curl-7_52_0","curl-7_51_0","curl-7_50_3","curl-7_50_2","curl-7_50_1","curl-7_50_0","curl-7_49_1","curl-7_49_0","curl-7_48_0","curl-7_47_1","curl-7_47_0","curl-7_46_0","curl-7_45_0","curl-7_44_0","curl-7_43_0","curl-7_42_1","curl-7_42_0","curl-7_41_0","curl-7_40_0","curl-7_39_0","curl-7_38_0","curl-7_37_1","curl-7_37_0","curl-7_36_0","curl-7_35_0","curl-7_34_0","curl-7_33_0","curl-7_32_0","curl-7_31_0","curl-7_30_0","curl-7_29_0","curl-7_28_1","curl-7_28_0","curl-7_27_0","curl-7_26_0","curl-7_25_0","curl-7_24_0","curl-7_23_1","curl-7_23_0","curl-7_22_0","curl-7_21_7","curl-7_21_6","curl-7_21_5","curl-7_21_4","curl-7_21_3","curl-7_21_2","curl-7_21_1","curl-7_21_0","curl-7_20_1","curl-7_20_0","curl-7_19_7","curl-7_19_6","curl-7_19_5","curl-7_19_4","curl-7_19_3","curl-7_19_2","curl-7_19_1","curl-7_19_0","curl-7_18_2","curl-7_18_1","curl-7_18_0","curl-7_17_1","curl-7_17_0","curl-7_17_0-preldapfix","curl-7_16_4","curl-7_16_3","curl-7_16_2","curl-7_16_1","curl-7_16_0","curl-7_15_6-prepipeline","curl-7_15_5","curl-7_15_4","curl-7_15_3","curl-7_15_2","curl-7_15_1","curl-7_15_0","curl-7_14_1","curl-7_14_0","curl-7_13_2","curl-7_13_1","before_ftp_statemachine","curl-7_13_0","curl-7_12_3"],"database_specific":{"source":"https://curl.se/docs/CURL-CVE-2018-1000120.json","vanir_signatures":[{"deprecated":false,"digest":{"line_hashes":["186785845436151373612249911977958489167","139368412014933340594086933420174292978","70225530077095739146651377461514758151","315143483916214608334710777218089290124","330558257654468377878934021755801694908","254969999324771221931386190909434168886","314505041855647615494139870984025356690","193603554521551770788174899501257487744","218104536554178230123180371501278426620","249311429039464347119097856005670027110","1949081060692883523800352474588507207","213361387690354360733145989391887781117","208717138941869647486339912054043560965","269526386197135474816625635309184114445","66234633984291063582401520848155751934","309919340248357245579399319652351958555"],"threshold":0.9},"id":"CURL-CVE-2018-1000120-1a41fdc7","signature_type":"Line","signature_version":"v1","source":"https://github.com/curl/curl.git/commit/535432c0adb62fe167ec09621500470b6fa4eb0f","target":{"file":"lib/ftp.c"}},{"deprecated":false,"digest":{"function_hash":"165261537492784234712649842191490061433","length":925},"id":"CURL-CVE-2018-1000120-3930517d","signature_type":"Function","signature_version":"v1","source":"https://github.com/curl/curl.git/commit/535432c0adb62fe167ec09621500470b6fa4eb0f","target":{"file":"lib/ftp.c","function":"ftp_state_list"}},{"deprecated":false,"digest":{"function_hash":"53816560832323379067076410399629338950","length":3107},"id":"CURL-CVE-2018-1000120-3dc55c90","signature_type":"Function","signature_version":"v1","source":"https://github.com/curl/curl.git/commit/535432c0adb62fe167ec09621500470b6fa4eb0f","target":{"file":"lib/ftp.c","function":"ftp_parse_url_path"}},{"deprecated":false,"digest":{"function_hash":"250530457694557457073913850752791544424","length":4608},"id":"CURL-CVE-2018-1000120-e7d820bb","signature_type":"Function","signature_version":"v1","source":"https://github.com/curl/curl.git/commit/535432c0adb62fe167ec09621500470b6fa4eb0f","target":{"file":"lib/ftp.c","function":"ftp_done"}}],"vanir_signatures_modified":"2026-05-27T02:29:24Z"}}],"database_specific":{"CWE":{"desc":"Heap-based Buffer Overflow","id":"CWE-122"},"URL":"https://curl.se/docs/CVE-2018-1000120.json","affects":"both","last_affected":"7.58.0","package":"curl","severity":"High","www":"https://curl.se/docs/CVE-2018-1000120.html"},"credits":[{"name":"Duy Phan Thanh","type":"FINDER"},{"name":"Daniel Stenberg","type":"REMEDIATION_DEVELOPER"}]}