CVE-2020-20949: n/a vulnerability

CVE-2020-20949: Bleichenbacher's attack on PKCS #1 v1.5 padding for RSA in STM32 cryptographic firmware library software ex...

Bleichenbacher's attack on PKCS #1 v1.5 padding for RSA in STM32 cryptographic firmware library software expansion for STM32Cube (UM1924). The vulnerability can allow one to use Bleichenbacher's oracle attack to decrypt an encrypted ciphertext by making successive queries to the server using the vulnerable library, resulting in remote information disclosure.

UnknownCVSS not scoredNot KEV-listedUpdatedJul 9, 2026, 00:09 UTC (UTC+00:00)

Security readout for executives and security teams

CVE-2020-20949 describes a cryptographic weakness in the STM32 cryptographic firmware library expansion for STM32Cube. Systems using the vulnerable RSA PKCS #1 v1.5 decryption behavior could leak encrypted information through repeated server queries. Exposure is most likely in embedded products or services built with STM32Cube cryptographic firmware library components that perform RSA PKCS #1 v1.5 decryption and expose queryable behavior to remote clients. Treat this as a targeted exposure review for embedded products rather than an internet-wide emergency. Escalate priority if customer-facing or remote interfaces use the affected cryptographic library behavior. Mitigation focus: Inventory products using STM32Cube cryptographic firmware library or X-CUBE-CRYPTOLIB.; Check STMicroelectronics guidance for affected versions and supported updates.; Prioritize systems exposing RSA PKCS #1 v1.5 decryption to untrusted clients..

Prepared: Jul 11, 2026, 12:20 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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Vulnerability profileCVE Program record

Severity: Unknown
CVSS: Not scored
Known Exploited: No
Published: Jan 20, 2021, 15:42 UTC (UTC+00:00)

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors

3Timeline events

1ADP providers

3Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
Aug 13, 2020, 00:00 UTC (UTC+00:00)
CVE publishedCVE Program
The CVE record was published.
Jan 20, 2021, 15:42 UTC (UTC+00:00)
CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
Jul 9, 2026, 00:09 UTC (UTC+00:00)

ADP provider summaries

Source materials

CVE List V5 sourceCVE List V5
https://www.st.com/en/embedded-software/x-cube-cryptolib.htmlCVE reference, mitre
https://bi-zone.medium.com/silence-will-fall-or-how-it-can-take-2-years-to-get-your-vuln-registered-e6134846f5bbCVE reference, mitre

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus

n/an/an/aListed

Weakness

CWE details

No CWE listed

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