CVE-2018-10903
mediumpriority · track · 31EPSS 0.032 · 88 %ileEUUSEPSS · scored 2026-10-28
A flaw was found in python-cryptography versions between >=1.9.0 and <2.3. The finalize_with_tag API did not enforce a minimum tag length. If a user did not validate the input length prior to passing it to finalize_with_tag an attacker could craft an invalid payload with a shortened tag (e.g. 1 byte) such that they would have a 1 in 256 chance of passing the MAC check. GCM tag forgeries can cause key leakage.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5–7.5
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (6)
Products and version ranges known to be affected.
- cryptography python-cryptography1.9.0 → 2.3nvdUScpe:2.3:a:cryptography:python-cryptography:*:*:*:*:*:*:*:*
advisories (2)
Vendor and ecosystem advisories describing this.
- GHSA-fcf9-3qw3-gxmjPyCA Cryptography vulnerable to GCM tag forgery2018-07-31ghsa · osvUS
A flaw was found in python-cryptography versions between >=1.9.0 and <2.3. The finalize_with_tag API did not enforce a minimum tag length. If a user did not validate the input length prior to passing it to finalize_with_tag an attacker could craft an invalid payload with a shortened tag (e.g. 1 byte) such that they would have a 1 in 256 chance of passing the MAC check. GCM tag forgeries can cause key leakage.
- PYSEC-2018-522018-07-30vendor · osvUS
A flaw was found in python-cryptography versions between >=1.9.0 and <2.3. The finalize_with_tag API did not enforce a minimum tag length. If a user did not validate the input length prior to passing it to finalize_with_tag an attacker could craft an invalid payload with a shortened tag (e.g. 1 byte) such that they would have a 1 in 256 chance of passing the MAC check. GCM tag forgeries can cause key leakage.
also known as (6)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (14)
External citations — patches, advisories, analysis.
- https://access.redhat.com/errata/RHSA-2018:3600cnnvd
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10903cnnvd
- https://github.com/pyca/cryptography/pull/4342/commits/688e0f673bfbf43fa898994326c6877f00ab19efcnnvd
- https://usn.ubuntu.com/3720-1/cnnvd
- https://www.auscert.org.au/bulletins/ESB-2020.1066/cnnvd
- https://www.auscert.org.au/bulletins/ESB-2022.6015cnnvd
- https://access.redhat.com/errata/RHSA-2018:3600enisa_euvd
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10903enisa_euvd
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