CVE-2023-32691 — gost
MEDIUMCVE-2023-32691 is a medium-severity (CVSS 5.9) CWE-203 vulnerability in github.com/ginuerzh/gost. 1 public exploit reference exists, so weaponization risk is real. No vendor fix is recorded yet; mitigation options are listed below.
ginuerzh/gost vulnerable to Timing Attack
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-32691.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2023-32691 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/ginuerzh/gostReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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.
Remediation
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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/ginuerzh/gost | all versions | No fix |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/ginuerzh/gost, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of github.com/ginuerzh/gost has shipped for CVE-2023-32691 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2023-32691 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-32691. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-32691 in your dependencies?
O3 Security finds CVE-2023-32691 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.