Summary
ginuerzh/gost vulnerable to Timing Attack
Timing attacks 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.
More information on this attack type can be found in this blog post.
Root Cause Analysis
In this case, the vulnerability occurs due to the following code.
https://github.com/ginuerzh/gost/blob/1c62376e0880e4094bd3731e06bd4f7842638f6a/auth.go#L46-L46
Here, a untrusted input, sourced from a HTTP header, is compared directly with a secret.
Since, this comparision is not secure, an attacker can mount a side-channel timing attack to guess the password.
Impact
CVE-2023-32691 has a CVSS score of 5.9 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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This can be easily fixed using a constant time comparing function such as crypto/subtle's ConstantTimeCompare.
An example fix can be found in https://github.com/runatlantis/atlantis/commit/48870911974adddaa4c99c8089e79b7d787fa820 Alternatively, one can apply the patch below
From d18cff85e1a565f688f717fd8f2cacea62ff9dbf Mon Sep 17 00:00:00 2001
From: Porcupiney Hairs <[email protected]>
Date: Sun, 7 May 2023 01:03:33 +0530
Subject: [PATCH] Fix : Timing attack
---
auth.go | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/auth.go b/auth.go
index 1be96e9..be13f23 100644
--- a/auth.go
+++ b/auth.go
@@ -2,6 +2,7 @@ package gost
import (
"bufio"
+ "crypto/subtle"
"io"
"strings"
"sync"
@@ -43,7 +44,8 @@ func (au *LocalAuthenticator) Authenticate(user, password string) bool {
}
v, ok := au.kvs[user]
- return ok && (v == "" || password == v)
+ passOk := subtle.ConstantTimeCompare([]byte(password), []byte(v)) == 0
+ return ok && (v == "" || passOk)
}
// Add adds a key-value pair to the Authenticator.
--
2.25.1
Frequently Asked Questions
- What is CVE-2023-32691? CVE-2023-32691 is a medium-severity security vulnerability in github.com/ginuerzh/gost (go), affecting versions <= 2.11.5. No fixed version is listed yet.
- How severe is CVE-2023-32691? CVE-2023-32691 has a CVSS score of 5.9 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/ginuerzh/gost are affected by CVE-2023-32691? github.com/ginuerzh/gost (go) versions <= 2.11.5 is affected.
- Is there a fix for CVE-2023-32691? No fixed version is listed for CVE-2023-32691 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2023-32691 exploitable, and should I be worried? Whether CVE-2023-32691 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2023-32691 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.