Cisco IOS XE Software Secure Boot Bypass Vulnerabilities

🚨SEVERITY: MEDIUM — CVSS 6.7Security Advisory

TL;DR 📌

  • Multiple vulnerabilities in Cisco IOS XE Software could allow an authenticated, local attacker with level-15 privileges or an unauthenticated attacker with physical access to an affected device to execute persistent code at boot time and break the chain of trust. These vulnerabilities are due improper validation of software packages. An attacker could exploit these vulnerabilities…
  • Highest CVSS: 6.7 (Medium).
  • Check the advisory for fixed releases — remediation detail is in the vendor link below.
  • CVEs: CVE-2025-20313, CVE-2025-20314.

What it is

Two related vulnerabilities affect the secure boot process in Cisco IOS XE Software: CVE-2025-20313 and CVE-2025-20314, both rated CVSS 6.7 (medium) with vector AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H. Despite the medium score, Cisco has raised the Security Impact Rating for this advisory from Medium to High, because the flaws let an attacker defeat a core integrity control rather than just gain a foothold.

The root cause is improper validation of software packages. An attacker who can place a crafted file into a specific location on the device can get that file treated as trusted, allowing persistent code execution on the underlying operating system at boot time. Because this happens during the boot sequence, the code survives reboots and the device’s chain of trust — the mechanism that is supposed to guarantee only signed, verified software runs — is broken.

Reaching the flaw requires either an authenticated local attacker holding privilege level 15 (effectively full administrative rights on the box), or an unauthenticated attacker with physical access to the device. This is not a remotely reachable network-facing bug; the attack vector is local (AV:L), and there’s no indication of a data-plane or management-plane network path to exploitation.

The advisory covers a broad set of hardware: routers and switches including the 1000, 4000, 8100 and 8400 Series ISRs/Secure Routers, ASR 1000, various Catalyst 8000-series edge platforms, Catalyst 9200 switches, Catalyst IE/IR ruggedised switches and routers, ESS9300, IE3500, and VG410 voice gateways, each with its own first-affected IOS XE release listed in the advisory. Cisco has confirmed that IOS, IOS XR and NX-OS are not affected — this is IOS XE specific.

What to do

  • Treat this as a boot-integrity issue, not a routine patch cycle item — the impact is a broken chain of trust with persistent code execution, even though local/physical access is required.
  • There are no workarounds. Upgrading to fixed IOS XE software is the only remediation Cisco offers.
  • Use the Cisco Software Checker against your running release to get the exact “First Fixed” and “Combined First Fixed” version for your platform; the advisory does not list a single fixed version because it varies per hardware platform and current release.
  • Cross-check your device model and current IOS XE version against the advisory’s affected-platform table (first-affected releases start as early as 17.3.1 depending on platform) to confirm exposure before assuming you’re clear.
  • Since one path requires local privilege level 15, review who holds that level of access and tighten AAA/authentication controls accordingly; since the other path requires physical access, ensure console and physical security controls (locked racks, port security, tamper monitoring) are in place for exposed hardware.
  • Note this is not in CISA’s KEV catalogue and Cisco PSIRT reports no public exploitation, so prioritise based on your own exposure (privileged-user population size, physical accessibility of devices) rather than urgency signals from active attack.

For leadership 🧭

Executive summary. Cisco IOS XE routers and switches across many product lines can have their secure boot integrity permanently broken by an admin-level or physically-present attacker, resulting in persistent, undetectable code execution. There is no workaround, so remediation depends entirely on scheduling firmware upgrades, though the access requirements mean this is not an urgent, drop-everything fix.

Why it matters:

  • A successful exploit plants code that survives reboots and defeats the guarantee that only signed, verified IOS XE software runs on the box.
  • Exploitation needs either level-15 administrative credentials or physical access to the device, so exposure tracks directly to how tightly you control privileged accounts and equipment racks.
  • The affected list spans a wide range of hardware — ISRs, ASR 1000, Catalyst 8000-series edge platforms, Catalyst 9200 switches, ruggedised IE/IR switches and routers, and VG410 gateways — each with its own first-affected release.
  • Cisco has no workaround on offer; the only remediation path is upgrading to a fixed IOS XE build, identified per platform via the Software Checker.

Now / Next / Later:

  • Now: Run your current IOS XE release numbers for each affected platform through Cisco’s Software Checker to get the exact First Fixed version, and confirm which of your devices actually appear on the affected hardware list.
  • Next: Schedule upgrades to the fixed IOS XE releases for confirmed vulnerable devices, prioritising any boxes with weak physical security or a large pool of level-15 administrators.
  • Later: Tighten AAA controls around who holds privilege level 15 and formalise physical security measures — locked racks, port security, tamper monitoring — for exposed IOS XE hardware to close off both exploitation paths going forward.

Source