efibootguard is a simple UEFI boot loader with support for safely switching between current and updated partition sets. Insufficient or missing validation and sanitization of input from untrustworthy bootloader environment files can cause crashes and probably also code injections into bg_setenv) or programs using libebgenv. This is triggered when the affected components try to modify a manipulated environment, in particular its user variables. Furthermore, bg_printenv may crash over invalid read accesses or report invalid results. Not affected by this issue is EFI Boot Guard's bootloader EFI binary. EFI Boot Guard release v0.15 contains required patches to sanitize and validate the bootloader environment prior to processing it in userspace. Its library and tools should be updated, so should programs statically linked against it. An update of the bootloader EFI executable is not required. The only way to prevent the issue with an unpatched EFI Boot Guard version is to avoid accesses to user variables, specifically modifications to them.
CVE-2023-39950
This medium-severity CVE scores 6.1 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 69% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 6.1
- EG Score
- 6.1(medium)
- EG Risk
- 28(Track)EG Risk 28/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity61% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 32%
- KEV
- Not listed
Published
August 14, 2023
Last Modified
November 21, 2024
References (10)
- security-advisories@githubhttps://github.com/siemens/efibootguard/blob/master/docs/API.md
- security-advisories@githubhttps://github.com/siemens/efibootguard/blob/master/docs/TOOLS.md
- security-advisories@githubhttps://github.com/siemens/efibootguard/blob/master/docs/TOOLS.md#setting-user-variables
- security-advisories@githubhttps://github.com/siemens/efibootguard/security/advisories/GHSA-j6pp-7g99-24m7
- security-advisories@githubhttps://github.com/siemens/efibootguard/tags
- af854a3a-2127-422b-91ae-364da2661108https://github.com/siemens/efibootguard/blob/master/docs/API.md
- af854a3a-2127-422b-91ae-364da2661108https://github.com/siemens/efibootguard/blob/master/docs/TOOLS.md
- af854a3a-2127-422b-91ae-364da2661108https://github.com/siemens/efibootguard/blob/master/docs/TOOLS.md#setting-user-variables
- af854a3a-2127-422b-91ae-364da2661108https://github.com/siemens/efibootguard/security/advisories/GHSA-j6pp-7g99-24m7
- af854a3a-2127-422b-91ae-364da2661108https://github.com/siemens/efibootguard/tags
Affected Packages
(3 across 3 ecosystems)
Debian:12(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| efibootguard | 0.13-2, 0.13-2+deb12u1~bpo11+1 | 0.13-2+deb12u1 | — |
Debian:13(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| efibootguard | — | 0.15-1 | — |
Debian:14(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| efibootguard | — | 0.15-1 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 7× in last 7d / 43× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
Showing the most recent 100 of 130 total refreshes for this CVE.
- 2026-08-09 13:44 UTCEPSS rescore
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- 2026-07-22 23:12 UTCEG score recompute
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- 2026-06-27 12:34 UTCOSV refresh
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- 2026-06-08 14:16 UTCEPSS rescore
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- 2026-06-07 15:23 UTCEPSS rescore
Related CVEs(same CWE)
Same CWE
10 shownCWE-20
- CVE-2005-0050EG 10.0EPSS p99HIGH
- CVE-2004-1019EG 10.0EPSS p94HIGH
- CVE-2004-0840EG 10.0EPSS p98HIGH
- CVE-2003-1425EG 10.0EPSS p96HIGH
- CVE-2003-1487EG 10.0EPSS p94HIGH
- CVE-2002-1874EG 10.0HIGH
- CVE-2002-2236EG 10.0EPSS p91HIGH
- CVE-2002-2365EG 10.0HIGH
- CVE-2002-1358EG 10.0EPSS p92HIGH
- CVE-2002-1359EG 10.0EPSS p100HIGH
Frequently asked(5)
What is CVE-2023-39950?
When was CVE-2023-39950 disclosed?
Is CVE-2023-39950 actively exploited?
What is the CVSS score of CVE-2023-39950?
How do I remediate CVE-2023-39950?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2023-39950
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