Security readout for executives and security teams
Plain-English summary
This CVE describes a timing information leak in Pengutronix barebox digest verification through version 2021.07.0. In business terms, it affects embedded or appliance firmware using barebox, not general desktops. The public data does not provide CVSS, confirmed exploitation, or a complete affected-product list.
Executive priority
Treat this as an embedded firmware exposure review item. Escalate if barebox controls secure boot or update verification for externally managed products; otherwise handle through normal firmware maintenance.
Technical view
The issue is in crypto/digest.c, where digest verification used memcmp. Because memcmp can return earlier depending on matching bytes, verification may expose timing differences. The referenced upstream commit is the key remediation artifact, but the source bundle does not name a fixed release.
Likely exposure
Exposure is most likely in embedded products, appliances, or custom firmware images built with Pengutronix barebox through 2021.07.0 and using digest verification for boot or update trust decisions.
Exploitation context
The source bundle marks KEV as false and provides no cited claim of active exploitation. Practical risk depends on whether an attacker can repeatedly trigger digest verification and measure timing accurately in the target environment.
Researcher notes
Evidence is limited to the CVE description and linked upstream material. No CVSS, CWE, CPE, exploit status, or named fixed release is provided in the bundle, so validation should focus on source provenance and firmware composition.
Mitigation direction
- Inventory firmware and products for barebox through 2021.07.0.
- Review the referenced upstream commit and vendor guidance.
- Update to a barebox build that contains the digest verification fix.
- Assess whether digest verification protects boot, update, or recovery flows.
- Prioritize vendor-supported firmware updates for deployed appliances.
Validation and detection
- Confirm whether barebox is present in firmware SBOMs or build manifests.
- Check the deployed barebox version against 2021.07.0 or earlier.
- Verify digest verification no longer relies on memcmp behavior.
- Confirm the remediation commit is included in the firmware source tree.
- Run normal boot and firmware update regression tests after updating.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-37847 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/saschahauer/barebox/commit/0a9f9a7410681e55362f8311537ebc7be9ad0fbeCVE reference · x_refsource_MISC
- https://gist.github.com/gquere/816dfadbad98745090034100a8a651ebCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.