AIKIDO-2026-340840
robrichards/xmlseclibs is vulnerable to Observable Discrepancy
59
Medium Risk
This Affects:
robrichards/xmlseclibsTL;DR
XMLSecEnc supports RSA PKCS#1 v1.5 (rsa-1_5) key transport and returns decryption errors that distinguish padding failures from other failures, while locateKey() accepts an attacker-chosen EncryptionMethod algorithm taken from the document. Together these expose a Bleichenbacher padding oracle that can recover the transported session key and decrypt content. Distinguishable exception types and messages let the oracle be built from either the symmetric or the RSA path. The fix denies RSA-1.5 key transport by default, normalizes decryption errors, and applies RFC 3218 random session-key substitution on invalid padding.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range and you decrypt XML that uses RSA key transport from untrusted sources.
Background info
robrichards/xmlseclibs is vulnerable to Observable Discrepancy in versions 0.0.1 - 3.1.5.
How to fix this
Upgrade the robrichards/xmlseclibs library to the patch version.
Are You Affected?
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