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Vulnerability · Published Aug 31, 2026 · Assigned by GitHub_M

CVE-2026-53508oasdiff does not enforce --allow-external-refs=false on the git-revision load path (SSRF / local file read)

Medium 6.0

In plain English

A medium-severity server-side request forgery in oasdiff from oasdiff. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 43% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)6.0Medium
Exploit odds (30 days)0.5%top 56.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

oasdiff is a command-line and Go package that compares and detects breaking changes in OpenAPI specs. From version 1.13.2 through version 1.18.0, oasdiff did not enforce --allow-external-refs=false (library: openapi3.Loader.IsExternalRefsAllowed = false) when loading a spec from a git revision (the rev:path form, e.g. main:openapi.yaml). External $refs were resolved on that load path even when external refs were explicitly disabled, so the mitigation silently did not apply there. This issue has been patched in version 1.18.1.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Gogithub.com/oasdiff/oasdiff1.18.1GHSA-2jcc-mxv7-p3f9
Gogithub.com/oasdiff/oasdiff1.18.1GO-2026-5937

Affected products (as reported)

VendorProductVersions
oasdiff oasdiff >= 1.13.2, < 1.18.1

Weakness: CWE-73, CWE-693, CWE-918 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

References