CVE-2025-34027: The Versa Concerto SD-WAN orchestration platform is vulnerable to an authentication bypass in the Traefik reve

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CRITICAL 9.0REMOTEUPGRADE

CVE-2025-34027 is a critical-severity flaw (CVSS 9.0) affecting concerto. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The Versa Concerto SD-WAN orchestration platform is vulnerable to an authentication bypass in the Traefik reverse proxy configuration, allowing at attacker to access administrative endpoints. The Spack upload endpoint can be leveraged for a Time-of-Check to Time-of-Use (TOCTOU) write in combination with a race condition to achieve remote code execution via path loading manipulation, allowing an unauthenticated actor to achieve remote code executi

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.0 (Critical)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	46.4% (top 1%)
CISA exploited list	No
Weakness	CWE-367
Published	2025-05-21
Last modified	2026-08-25

Publisher (CNA): VulnCheck · Vendor: versa-networks

Last updated 2026-08-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-05-21 22:15 UTCPublished CVE record published
2026-08-25 15:04 UTCUpdated Record last modified

versa-networks concerto UPGRADE

Affected: >= 11.4.0 and <= 12.1.1 · 12.1.2 · 12.2.1

Fixed in: newer than 12.1.1

Safe to downgrade to: a release before 11.4.0

1. Check installed version

apt-cache policy concerto || rpm -q concerto || concerto --version

2. UPGRADE to newer than 12.1.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade concerto

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade concerto

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 11.4.0 (Debian / Ubuntu)

apt-cache madison concerto sudo apt install concerto=<VERSION_BEFORE_11.4.0> sudo apt-mark hold concerto

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list concerto sudo dnf downgrade concerto-<VERSION_BEFORE_11.4.0> sudo dnf versionlock add concerto

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Fedora ELN · fips-provider-next · FIXED · 1.5.3-3.eln159 · FEDORA-2026-3ce99ec7df · source

sudo dnf upgrade --advisory=FEDORA-2026-3ce99ec7df

Fedora 46 · rubygem-webmock · FIXED · 3.26.1-3.fc46 · FEDORA-2026-bb57b4d095 · source

sudo dnf upgrade --advisory=FEDORA-2026-bb57b4d095

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: projectdiscovery.io/blog/versa-concerto-authentication-bypass-rce
Nuclei scan template: Versa Concerto API Path Based - Authentication Bypass

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-34027?

concerto: upgrade to newer than 12.1.1. Exact commands for each OS are on this page.

Is CVE-2025-34027 being exploited?

CVE-2025-34027 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-34027 affect?

CVE-2025-34027 affects concerto. Severity is critical (CVSS 9.0). The Versa Concerto SD-WAN orchestration platform is vulnerable to an authentication bypass in the Traefik reverse proxy configuration, allowing at attacker to access administrative endpoints. The Spack upload endpoint can be leveraged for a

How urgent is CVE-2025-34027?

Priority 69/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Software pages

Traefik vulnerabilities

Related CVEs

CVE-2025-34025 HIGH 8.8 DOWNGRADE The Versa Concerto SD-WAN orchestration platform is vulnerable to an privileges escalation and container escap
CVE-2025-34026 HIGH 7.5 EXPLOITED UPGRADE Versa Concerto Improper Authentication Vulnerability

References

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