{"id":"CVE-2023-32691","aliases":["EUVD-2023-1611","GHSA-qjrq-hm79-49ww"],"status":"published","title":"ginuerzh/gost vulnerable to Timing Attack","description":"gost (GO Simple Tunnel) is a simple tunnel written in golang. Sensitive secrets such as passwords, token and API keys should be compared only using a constant-time comparison function. Untrusted input, sourced from a HTTP header, is compared directly with a secret. Since this comparison is not secure, an attacker can mount a side-channel timing attack to guess the password. As a workaround, this can be easily fixed using a constant time comparing function such as `crypto/subtle`'s `ConstantTimeCompare`.","severity":{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00574,"percentile":0.47657,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-203"],"published":"2023-05-22T19:47:15Z","modified":"2026-10-28T02:30:40Z","affected":[{"source":"ghsa","ecosystem":"Go","package":"github.com/ginuerzh/gost","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"2.11.5"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/ginuerzh/gost","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"last_affected":"2.11.5"}]}]}],"products":[{"vendor":"ginuerzh","product":"gost"},{"vendor":"go_simple_tunnel_project","product":"go_simple_tunnel"}],"references":[{"url":"https://github.com/ginuerzh/gost/security/advisories/GHSA-qjrq-hm79-49ww","tags":["x_refsource_CONFIRM","x_transferred","Exploit","Vendor Advisory","advisory","web"]},{"url":"https://github.com/ginuerzh/gost/blob/1c62376e0880e4094bd3731e06bd4f7842638f6a/auth.go#L46","tags":["x_refsource_MISC","x_transferred","Product","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-32691","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-qjrq-hm79-49ww"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/32xxx/CVE-2023-32691.json","tags":["advisory"]},{"url":"https://github.com/ginuerzh/gost","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2023-32691","title":"ginuerzh/gost vulnerable to Timing Attack","description":"gost (GO Simple Tunnel) is a simple tunnel written in golang. Sensitive secrets such as passwords, token and API keys should be compared only using a constant-time comparison function. Untrusted input, sourced from a HTTP header, is compared directly with a secret. Since this comparison is not secure, an attacker can mount a side-channel timing attack to guess the password. As a workaround, this can be easily fixed using a constant time comparing function such as `crypto/subtle`'s `ConstantTimeCompare`. \n","status":"published","published":"2023-05-30T03:06:06.08Z","modified":"2025-01-10T20:45:20Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-203"],"updated_at":"2026-11-02T14:35:29.381004Z"}],"euvd":[{"id":"EUVD-2023-1611","description":"gost (GO Simple Tunnel) is a simple tunnel written in golang. Sensitive secrets such as passwords, token and API keys should be compared only using a constant-time comparison function. Untrusted input, sourced from a HTTP header, is compared directly with a secret. Since this comparison is not secure, an attacker can mount a side-channel timing attack to guess the password. As a workaround, this can be easily fixed using a constant time comparing function such as `crypto/subtle`'s `ConstantTimeCompare`. \n","status":"published","published":"2023-05-30T03:06:06Z","modified":"2025-01-10T20:45:20Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N","level":"medium"}],"updated_at":"2026-11-03T00:04:21.239531Z"}],"ghsa":[{"id":"GHSA-qjrq-hm79-49ww","title":"ginuerzh/gost vulnerable to Timing Attack","description":"[Timing attacks](https://en.wikipedia.org/wiki/Timing_attack) occur when an attacker can guess a secret by observing a difference in processing time for valid and invalid inputs. Sensitive secrets such as passwords, token and API keys should be compared only using a constant-time comparision function.\nMore information on this attack type can be found in [this blog post](https://verboselogging.com/2012/08/20/a-timing-attack-in-action). \n\n# Root Cause Analysis\n\nIn this case, the vulnerability occurs due to the following code.\n\nhttps://github.com/ginuerzh/gost/blob/1c62376e0880e4094bd3731e06bd4f7842638f6a/auth.go#L46-L46\n\nHere, a untrusted input, sourced from a HTTP header, is compared directly with a secret. \nSince, this comparision is not secure, an attacker can mount a side-channel timing attack to guess the password.\n\n# Remediation\n\nThis can be easily fixed using a constant time comparing function such as `crypto/subtle`'s `ConstantTimeCompare`. \nAn example fix can be found in https://github.com/runatlantis/atlantis/commit/48870911974adddaa4c99c8089e79b7d787fa820 Alternatively, one can apply the patch below\n\n```\nFrom d18cff85e1a565f688f717fd8f2cacea62ff9dbf Mon Sep 17 00:00:00 2001\nFrom: Porcupiney Hairs \u003cporcupiney.hairs@protonmail.com\u003e\nDate: Sun, 7 May 2023 01:03:33 +0530\nSubject: [PATCH] Fix : Timing attack\n\n---\n auth.go | 4 +++-\n 1 file changed, 3 insertions(+), 1 deletion(-)\n\ndiff --git a/auth.go b/auth.go\nindex 1be96e9..be13f23 100644\n--- a/auth.go\n+++ b/auth.go\n@@ -2,6 +2,7 @@ package gost\n \n import (\n \t\"bufio\"\n+\t\"crypto/subtle\"\n \t\"io\"\n \t\"strings\"\n \t\"sync\"\n@@ -43,7 +44,8 @@ func (au *LocalAuthenticator) Authenticate(user, password string) bool {\n \t}\n \n \tv, ok := au.kvs[user]\n-\treturn ok \u0026\u0026 (v == \"\" || password == v)\n+\tpassOk := subtle.ConstantTimeCompare([]byte(password), []byte(v)) == 0\n+\treturn ok \u0026\u0026 (v == \"\" || passOk)\n }\n \n // Add adds a key-value pair to the Authenticator.\n-- \n2.25.1\n\n```","status":"published","published":"2023-05-22T19:47:15Z","modified":"2025-03-04T21:36:23Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N","level":"medium"}],"cwes":["CWE-203"],"updated_at":"2026-11-02T14:38:34.185137Z"}],"nvd":[{"id":"CVE-2023-32691","description":"gost (GO Simple Tunnel) is a simple tunnel written in golang. Sensitive secrets such as passwords, token and API keys should be compared only using a constant-time comparison function. Untrusted input, sourced from a HTTP header, is compared directly with a secret. Since this comparison is not secure, an attacker can mount a side-channel timing attack to guess the password. As a workaround, this can be easily fixed using a constant time comparing function such as `crypto/subtle`'s `ConstantTimeCompare`. \n","status":"published","published":"2023-05-30T04:15:09.98Z","modified":"2026-06-17T05:59:24.01Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-203"],"updated_at":"2026-11-02T14:08:03.795015Z"}],"osv":[{"id":"CVE-2023-32691","title":"ginuerzh/gost vulnerable to Timing Attack","description":"gost (GO Simple Tunnel) is a simple tunnel written in golang. Sensitive secrets such as passwords, token and API keys should be compared only using a constant-time comparison function. Untrusted input, sourced from a HTTP header, is compared directly with a secret. Since this comparison is not secure, an attacker can mount a side-channel timing attack to guess the password. As a workaround, this can be easily fixed using a constant time comparing function such as `crypto/subtle`'s `ConstantTimeCompare`. \n","status":"published","published":"2023-05-30T03:06:06.08Z","modified":"2026-10-28T02:30:40.93471374Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N","level":"medium"}],"cwes":["CWE-203"],"updated_at":"2026-11-02T15:44:32.116263Z"},{"id":"GHSA-qjrq-hm79-49ww","title":"ginuerzh/gost vulnerable to Timing Attack","description":"[Timing attacks](https://en.wikipedia.org/wiki/Timing_attack) occur when an attacker can guess a secret by observing a difference in processing time for valid and invalid inputs. Sensitive secrets such as passwords, token and API keys should be compared only using a constant-time comparision function.\nMore information on this attack type can be found in [this blog post](https://verboselogging.com/2012/08/20/a-timing-attack-in-action). \n\n# Root Cause Analysis\n\nIn this case, the vulnerability occurs due to the following code.\n\nhttps://github.com/ginuerzh/gost/blob/1c62376e0880e4094bd3731e06bd4f7842638f6a/auth.go#L46-L46\n\nHere, a untrusted input, sourced from a HTTP header, is compared directly with a secret. \nSince, this comparision is not secure, an attacker can mount a side-channel timing attack to guess the password.\n\n# Remediation\n\nThis can be easily fixed using a constant time comparing function such as `crypto/subtle`'s `ConstantTimeCompare`. \nAn example fix can be found in https://github.com/runatlantis/atlantis/commit/48870911974adddaa4c99c8089e79b7d787fa820 Alternatively, one can apply the patch below\n\n```\nFrom d18cff85e1a565f688f717fd8f2cacea62ff9dbf Mon Sep 17 00:00:00 2001\nFrom: Porcupiney Hairs \u003cporcupiney.hairs@protonmail.com\u003e\nDate: Sun, 7 May 2023 01:03:33 +0530\nSubject: [PATCH] Fix : Timing attack\n\n---\n auth.go | 4 +++-\n 1 file changed, 3 insertions(+), 1 deletion(-)\n\ndiff --git a/auth.go b/auth.go\nindex 1be96e9..be13f23 100644\n--- a/auth.go\n+++ b/auth.go\n@@ -2,6 +2,7 @@ package gost\n \n import (\n \t\"bufio\"\n+\t\"crypto/subtle\"\n \t\"io\"\n \t\"strings\"\n \t\"sync\"\n@@ -43,7 +44,8 @@ func (au *LocalAuthenticator) Authenticate(user, password string) bool {\n \t}\n \n \tv, ok := au.kvs[user]\n-\treturn ok \u0026\u0026 (v == \"\" || password == v)\n+\tpassOk := subtle.ConstantTimeCompare([]byte(password), []byte(v)) == 0\n+\treturn ok \u0026\u0026 (v == \"\" || passOk)\n }\n \n // Add adds a key-value pair to the Authenticator.\n-- \n2.25.1\n\n```","status":"published","published":"2023-05-22T19:47:15Z","modified":"2026-09-10T03:50:08.350758125Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N","level":"medium"}],"cwes":["CWE-203"],"updated_at":"2026-11-02T15:46:54.760124Z"}]}}