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GHSA-wcrf-9vrr-854f

CriticalCVSS 9.1 / 10
Published Jul 16, 2026·Last modified Jul 16, 2026
Affected Components(0)

No affected components available

Description

Impact

The to_absolute_normalized_path function (security.lua:28-43) does not collapse redundant path separators (// → /). On Linux, //etc/passwd is equivalent to /etc/passwd (POSIX path semantics), but is_critical_path fails to match the double-slash variant because //etc/passwd does not start with /etc/.

This allows Lua code submitted as an EnvoyExtensionPolicy to read arbitrary files from the gateway controller pod's filesystem during Strict validation (the default), including:

  • /etc/passwd
  • Kubernetes SA tokens via //var/run/secrets/kubernetes.io/serviceaccount/token
  • TLS certificates via //certs/...
  • Process environment via //proc/self/environ

These credentials can be used to read sensitive information from the K8s API Server or from the Gateway XDS server.

Patches

This has been patched in versions >= v1.7.4 and v1.8.1

  • Collapse redundant path separators (// to /) so double-slash variants like //etc/passwd and //var/run/secrets/... are matched by the critical-path check.
  • Rewrite the traversal check to reject any . or .. segment in any position and across both separator styles (catches /etc/./passwd, ./etc/passwd, /etc/.).

Workarounds

Please refer to the Warning section in Lua docs for measures to reduce risk.

Credits

Envoy Gateway thanks @dashingDragon and @Donjon-Cerberus for reporting this issue.

Risk Scores
Base Score
9.1

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a high impact on the confidentiality of the information. There is a low impact on the integrity of the data. There is a low impact on the availability of the system.

Threat Intelligence
8.3

Exploitation activity has been observed. Apply available patches or mitigations urgently.

EPSS
N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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Critical severity
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