OpenBSD OpenSSH Unexpected Status Code or Return Value Vulnerability

Known exploitedExploited · KEV 2026-11-09Public exploit code Trending #2CVE-2026-123158CWE-394

Exploited since 2026-11-09. No WAF vendor names it yet. 8 public exploit repos.

Edge rules

0/9

Our test

No exploit yet

CVSS

8.1

EPSS

1.0% Top 37%

Posts, 14d

539

Published

2026-11-05

What it is

sshd in OpenSSH before 10.6p2 on Linux, when musl libc is used without PAM, lacks a workaround for a password authentication bypass (related to misinterpretation of whether a string is intended to be a password hash). For some configurations of accounts, any password between 256 and 1024 characters succeeds. An example of a platform using musl libc without PAM is Alpine Linux.

Read the full descriptionShow less

From the CVE record · CVE-2026-123158 ↗

Known exploitedLast checked 2026-11-09

The risk

CISA lists CVE-2026-123158 as exploited in the wild since 2026-11-09. It is reachable over the network without credentials or any user interaction (CVSS 8.1). 8 public exploit repositories are on GitHub (unvetted). No edge WAF vendor names it in a changelog, so default managed rules may or may not catch it.

Who is affected

Teams running OpenBSD OpenSSH (before 10.6p2). Prioritise internet-facing instances.

Next steps

Find the version you run. On the host:
```
ssh -V
```
Apply the vendor's fix; the advisory lists the affected and fixed versions. openssh.org ↗
CISA's required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines. US federal agencies must act by 2026-11-12.
Review exposed instances for signs of compromise: it was exploited before many systems were patched, and a later patch does not undo access already gained.
Do not rely on WAF defaults: no edge vendor names this CVE. Restrict access to the vulnerable component or add a custom rule until it is patched. Edge coverage
Check which WAF sits in front of your site and whether it covers this CVE. Check your domain

Exploitation activity

Last 90 days

Honeypot days: 0 / 90
Last attempt seen: —
Listed exploited: 9 Nov CISA
Telegram claims: 2 days, unverified

Honeypot hits

Listings & reports

Telegram claims

Edge coverage

Claimed by vendors

CloudflareNo public claimNot named AWSNo public claimNot named Microsoft AzureNo public claimNot named Google CloudNo public claimNot named FastlyNo public claimNot named VercelNo public claimNot named F5No public claimNot named AkamaiNo public sourceNo public changelog OWASP CRSNo public claimNot named

Attack traffic on Cloudflare

Cloudflare Radar

Broken Authentication15% of mitigated layer 7 attacks, 7 days
Rules for named CVEs5.8% of mitigated layer 7 attacks, 7 days

Radar groups Cloudflare's WAF managed rules by category; it does not publish counts per CVE. These shares show how much attack traffic targets this kind of flaw across Cloudflare's network (28-day trend). They are not compromised systems, and seeing few attempts on Cloudflare does not prove an absence elsewhere. Radar data as of 2026-11-09. Radar ↗

Check your exposure with an agent

Read-only

Copy this into an agent with access to your infrastructure. It asks for an evidence-based, read-only assessment: affected systems, exposure, compensating controls and what is still unknown. It does not scan or change anything by itself.

Prompt12 lines

Assess whether the infrastructure available to you is affected by CVE-2026-123158 (OpenBSD OpenSSH Unexpected Status Code or Return Value Vulnerability). Perform a read-only assessment within your authorized access. Do not send exploit traffic, scan third-party systems, change configuration or restart services.

1. Verify the CVE record at https://www.cve.org/CVERecord?id=CVE-2026-123158 and the vendor advisory. Establish affected and fixed versions, including vendor backports. The record lists: OpenBSD OpenSSH: affected before 10.6p2. Cite sources and retrieval dates; flag anything you cannot verify.
2. Inventory deployments of OpenBSD OpenSSH: asset, environment, owner where known, installed version or build, and how you confirmed it (package metadata, a version endpoint, image tags), e.g. `ssh -V` (on the host). An image tag alone does not prove the running version.
3. Identify which deployments are reachable from the internet or untrusted networks, and through which paths (direct origin, load balancer, CDN or WAF).
4. Assess compensating controls separately from patch status. Current edge WAF coverage for this CVE: no edge WAF vendor names it. Live data: https://cve.vigilbase.com/api/v1/cves/CVE-2026-123158. Check whether the rule is enabled and in block mode on each path, and whether any path bypasses the WAF. A WAF rule is not a patch.
5. It is known exploited (CISA KEV): review logs on exposed instances for signs of exploitation before and after patching.

Return a short summary and a table: asset | version/build | assessment (affected, fixed, not applicable, unknown) | exposure | compensating control | evidence | next action. List what you could not assess and the access needed to resolve it. Do not infer absence of compromise from patch status or a lack of alerts.

Remediation guidance: Apply the vendor's fix; the advisory lists the affected and fixed versions. CISA's required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines. US federal agencies must act by 2026-11-12.
More: https://cve.vigilbase.com/cve/CVE-2026-123158

Sources

Cited

CVE record

CVSS 3.1 8.1 (high). Weakness: CWE-394.

CVE-2026-123158 ↗NVD ↗

Vendor advisory

Fixes and mitigations the CVE record links to. Check affected builds against the vendor, including backports.

openssh.org ↗alpinelinux.org ↗github.com ↗cisa.gov ↗

Exploit evidence

8 GitHub repositories claim exploit code (unvetted; don't run).

Exploit repositories

Seen exploited

Listed in an independent exploited-vulnerability catalog on 7 Nov 2026. Claimed in 2 Telegram posts (unverified).

CISA KEV

Added 2026-11-09, federal due date 2026-11-12 (catalog 2026.11.09, checked 2026-11-09).

CISA KEV catalog ↗

EPSS

1.01% probability of exploitation activity in the next 30 days, higher than 63% of CVEs (2026-11-08).

FIRST EPSS ↗

WAF vendor statements

No edge vendor changelog names it.

Ask Vigil

AI · answers from this page

Ask about CVE-2026-123158: who's covered, what to patch first, how vendors compare. I cite sources and won't help with attacks.

Severity, decoded

CVSS 3.1

8.1High

High · 8.1 / 10

Exploitable over the network under specific conditions, with no privileges and no user interaction, leading to full loss of confidentiality, integrity and availability.

Over the internetNo login neededNo user actionHard to pull offFull compromise

How the score is built8 metrics

Attack vectorAn attacker can reach it over the internet; no access to your network needed.
Network
Attack complexityThe attack only works when conditions outside the attacker's control line up.
High
Privileges requiredNo account or login is needed.
None
User interactionNo one has to click or open anything; the attack works on its own.
None
ScopeThe damage stays within the vulnerable component.
Unchanged
Confidentiality impactAn attacker can read all data the affected component holds, or the most sensitive parts of it.
High
Integrity impactAn attacker can change any data or files the affected component protects.
High
Availability impactAn attacker can take the component down completely or keep it from serving anyone.
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Public exploits

8 found

0 Metasploit0 Exploit-DB0 Scanner template8 GitHub PoCs

No exploit in Exploit-DB or Metasploit, and no scanner template. That lowers, but doesn't remove, the chance of mass exploitation.

Links are to third-party code: never run it outside an isolated lab.

Timeline

2026-11-05
CVE published
CVE List
2026-11-05
First public exploit repository
coboliqcom/cve-2026-123158-sshole-safe-rust
2026-11-05
First social mention we saw
2026-11-09
Added to CISA KEV
Confirmed exploitation in the wild

Vendor statements

Quoted

CloudflareWAF Managed RulesNo public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. Each row gives the rule ID and its default action. The feed starts in January 2025, so older rules are missing.

AWSAWS WAF Managed RulesNo public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. AWS often describes a vulnerability without naming its CVE (for example "Log4j"). We count only entries that name the CVE, so AWS coverage is understated.

Microsoft AzureFront Door and Application Gateway WAF (DRS)No public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. The rule tables name CVEs but carry no dates, so Azure is left out of every time-to-rule figure.

Google CloudCloud Armor preconfigured WAF rulesNo public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. Google names few CVEs: the release notes start in May 2024 and the rules reference lists CVEs without dates. Its cve-canary rules are opt-in.

FastlyNext-Gen WAF virtual patchesNo public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. The feed holds only the latest 25 changes, so history builds up from the day we started reading it.

VercelVercel WAF (platform rules)No public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. Vercel posts about the vulnerabilities it ships platform-wide rules for, on by default for every project, with no rule ids. When a post limits its claim to some advisories, we count only the ones it names. Projects not on Vercel get nothing from these rules.

F5Attack signatures (Distributed Cloud WAF)No public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. Each signature lists the CVEs it references, with its id and date. F5 does not state a default action; signatures enforce once staging ends in your policy.

AkamaiApp & API Protector (Adaptive Security Engine)No public source

This vendor publishes no machine-readable rule changelog we can check.

OWASP CRSCore Rule Set (open source, used inside many WAFs)No public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. CRS rarely names CVEs: it relies on generic detections. Our own lab measures what it actually blocks.

Is your site covered?

We find your CDN or WAF in public DNS and match it to this CVE. Nothing is sent to your site.

Vigilbase OS

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Our lab test

Measured

Nothing to replay yet

Exploit code exists (8 items below), but we only replay declarative request templates, never third-party exploit code. Flaws in kernels, libraries or VPN clients can't be reached through a WAF at all.

We'll test it within a minute of a template appearing in nuclei-templates.

Watching for templates · checked just now4,483 CVEs tested

Exposure

Estimates

No website count: OpenSSH isn't web software we can count from the outside.

1.0%chance of exploitation in 30 days

FIRST EPSS, updated daily. Top 37% of all CVEs by this score.

For agents

$ curl https://cve.vigilbase.com/api/v1/cves/CVE-2026-123158

MCP server Markdown CVE.org NVD