Summary
emp3r0r Affected by Concurrent Map Access DoS (panic/crash)
Multiple shared maps are accessed without consistent synchronization across goroutines. Under concurrent activity, Go runtime can trigger fatal error: concurrent map read and map write, causing C2 process crash (availability loss).
Vulnerable Component(with code examples)
Operator relay map had mixed access patterns (iteration and mutation without a single lock policy):
// vulnerable pattern (operator session map)
for sessionID, op := range OPERATORS { // iteration path
...
}
// concurrent mutation path elsewhere
OPERATORS[operatorSession] = &operator_t{...}
delete(OPERATORS, operatorSession)
Port-forwarding session map had read/write paths guarded inconsistently:
// vulnerable pattern (port forward map)
if sess, ok := PortFwds[id]; ok { // read path
...
}
PortFwds[id] = newSession // write path
delete(PortFwds, id) // delete path
FTP stream map similarly mixed concurrent iteration with mutation:
// vulnerable pattern (FTP stream map)
for token, stream := range FTPStreams { // iteration path
...
}
FTPStreams[token] = stream // write path
delete(FTPStreams, token) // delete path
Attack Vector
- Attacker (or stress traffic in authenticated flows) triggers high concurrency in normal control paths.
- Operator sessions connect/disconnect while message forwarding and file-transfer workflows are active.
- Concurrent read/write hits shared maps.
- Go runtime panics with concurrent map read/write error.
- C2 component exits, producing denial of service.
Proof of Concept
- Start C2 server with active operator session(s) in a lab environment.
- Generate rapid operator session churn (connect/disconnect loops).
- Simultaneously drive agent message tunnel traffic and/or file transfer activity.
- Observe crash signature in logs:
fatal error: concurrent map read and map write. - Optional: run with race detector in dev build to confirm race locations.
Impact
- C2 service interruption due to process panic/crash.
- Operational instability under load or deliberate churn.
- Repeated crash-restart cycles can degrade command reliability and incident response workflows.
Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing. Typical impact: TOCTOU exploits, data corruption, or privilege escalation.
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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Frequently Asked Questions
- What is CVE-2026-26201? CVE-2026-26201 is a high-severity race condition vulnerability in github.com/jm33-m0/emp3r0r/core (go), affecting versions < 0.0.0-20260212232424-ea4d074f081d. It is fixed in 0.0.0-20260212232424-ea4d074f081d. Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing.
- Which versions of github.com/jm33-m0/emp3r0r/core are affected by CVE-2026-26201? github.com/jm33-m0/emp3r0r/core (go) versions < 0.0.0-20260212232424-ea4d074f081d is affected.
- Is there a fix for CVE-2026-26201? Yes. CVE-2026-26201 is fixed in 0.0.0-20260212232424-ea4d074f081d. Upgrade to this version or later.
- Is CVE-2026-26201 exploitable, and should I be worried? Whether CVE-2026-26201 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-2026-26201 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.
- How do I fix CVE-2026-26201? Upgrade
github.com/jm33-m0/emp3r0r/coreto 0.0.0-20260212232424-ea4d074f081d or later.