CVE-2026-32313
Published: 16 March 2026
Summary
CVE-2026-32313 is a high-severity Improper Validation of Integrity Check Value (CWE-354) vulnerability in Xmlseclibs Project Xmlseclibs. Its CVSS base score is 8.2 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 4.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 RA-5 (Vulnerability Monitoring and Scanning) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-32313 affects xmlseclibs, a PHP library for handling XML Encryption and Signatures, in versions prior to 3.1.5. The vulnerability stems from a lack of validation for the authentication tag length in XML nodes encrypted using AES-128-GCM, AES-192-GCM, or AES-256-GCM. This flaw, classified under CWE-354 (Improper Validation of Integrity Check Value), enables cryptographic weaknesses in GCM mode processing, as rated 8.2 on the CVSS 3.1 scale (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N).
A remote attacker with network access requires no privileges or user interaction to exploit this issue. By crafting malformed ciphertexts, they can brute-force the authentication tag due to insufficient length checks, recover the GHASH key, and decrypt the protected XML nodes to access confidential data. Additionally, attackers can forge arbitrary ciphertexts without knowledge of the encryption key, potentially enabling integrity violations in XML-based systems relying on this library for secure processing.
The vulnerability is addressed in xmlseclibs version 3.1.5, which includes a fix via commit 03062be78178cbb5e8f605cd255dc32a14981f92. Security practitioners should upgrade to this release immediately, as detailed in the GitHub security advisory GHSA-4v26-v6cg-g6f9 and the corresponding release notes.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-12094
Vulnerability details
xmlseclibs is a library written in PHP for working with XML Encryption and Signatures. Prior to 3.1.5, XML nodes encrypted with either aes-128-gcm, aes-192-gcm, or aes-256-gcm lack validation of the authentication tag length. An attacker can use this to brute-force…
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an authentication tag, recover the GHASH key, and decrypt the encrypted nodes. It also allows to forge arbitrary ciphertexts without knowing the encryption key. This vulnerability is fixed in 3.1.5.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote unauthenticated network exploitation of XML encryption library directly maps to T1190; resulting decryption of protected nodes enables access to confidential data (T1005); GCM tag forgery enables manipulation of transmitted/encrypted data (T1565.002).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly mandates identification, prioritization, and timely remediation of flaws like the authentication tag length validation failure in xmlseclibs by patching to version 3.1.5.
Requires vulnerability scanning that identifies deployments of vulnerable xmlseclibs versions affected by CVE-2026-32313.
Ensures implementation of validated cryptographic protections to mitigate decryption and forgery risks from improper GCM authentication tag handling.