Security readout for executives and security teams
Plain-English summary
This flaw can make a local Linux name-service caching component crash while handling netgroup lookups. The expected business impact is limited service degradation or local denial of service, not data theft or remote compromise.
Executive priority
Treat this as routine patch management unless affected systems support critical authentication or directory workflows. It deserves tracking, but the cited impact is local availability degradation only.
Technical view
CVE-2021-27645 is a double-free in glibc nscd, related to netgroupcache.c, affecting glibc/libc6 2.29 through 2.33. The CVSS vector indicates local access, high attack complexity, low privileges, no user interaction, and low availability impact.
Likely exposure
Exposure is most likely on Linux systems running glibc/libc6 2.29 through 2.33 with nscd enabled and netgroup lookup paths in use. The source bundle does not identify specific vendor CPEs.
Exploitation context
The provided data does not show active exploitation, and the CVE is not listed as KEV. The scoring indicates local, high-complexity exploitation requiring low privileges, with impact limited to availability.
Researcher notes
The evidence points to CWE-415 double-free behavior in nscd netgroup handling. Public metadata is sparse on affected products beyond glibc versions, so validation should rely on installed package versions and distribution advisories.
Mitigation direction
- Apply relevant distribution glibc/libc6 security updates where available.
- Prioritize hosts using nscd and netgroup lookups.
- Check Fedora, Gentoo, Debian, or your OS vendor guidance.
- If no update is available, follow vendor-recommended compensating controls.
Validation and detection
- Inventory systems running glibc/libc6 2.29 through 2.33.
- Confirm whether nscd is installed, enabled, and used.
- Identify services depending on netgroup lookups.
- Review package advisory status against your distribution.
- Monitor affected hosts for repeated nscd crashes.
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.
CWE-415: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-27645 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
- Low
- CVSS
- 2.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
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 vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L11.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
2.5LowVector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://sourceware.org/bugzilla/show_bug.cgi?id=27462CVE reference
- FEDORA-2021-6749bfcfd9CVE reference · vendor-advisory
- FEDORA-2021-2ba993d6c5CVE reference · vendor-advisory
- GLSA-202107-07CVE reference · vendor-advisory
- [debian-lts-announce] 20221017 [SECURITY] [DLA 3152-1] glibc security updateCVE reference · mailing-list
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.
Double Free
Double Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.