Security readout for executives and security teams
Plain-English summary
This CVE describes a denial-of-service weakness in sha256crypt and sha512crypt through version 0.6. Very long password inputs can make hashing consume excessive CPU because work grows quadratically with password length. Business risk depends on whether exposed authentication or password-processing paths use these algorithms.
Executive priority
Treat this as an availability risk requiring inventory, not an emergency exploitation event. Prioritize internet-facing authentication services and shared infrastructure where CPU exhaustion could affect many users. Escalate if local systems confirm affected SHA-crypt use without input limits.
Technical view
The issue is algorithmic complexity: sha256crypt and sha512crypt runtime is proportional to the square of password length. An attacker-controlled long password can therefore increase CPU cost and degrade availability. The source bundle does not identify specific affected products, CVSS scoring, a named patch, or confirmed exploitation.
Likely exposure
Exposure is most likely where systems use sha256crypt or sha512crypt through 0.6 and accept untrusted password strings, especially public login, registration, password-change, or authentication-related workflows. The provided CVE data lists affected vendor and product as n/a, so product-level exposure must be verified locally.
Exploitation context
CISA KEV status is false in the provided bundle, and no cited source states active exploitation. The described abuse requires reaching code paths that hash attacker-controlled password input. Evidence supports denial of service through CPU consumption, not data theft or privilege escalation.
Researcher notes
The CVE record is sparse: no CVSS, CWE, vendor, product, or fix is provided. The key technical claim is quadratic runtime with password length. Validation should focus on implementation discovery, reachable password hashing paths, and whether operational controls cap attacker-controlled input size.
Mitigation direction
- Inventory use of sha256crypt and sha512crypt in authentication and password-processing code.
- Check vendor or distribution guidance for affected implementations and supported updates.
- Avoid accepting unbounded password lengths in exposed workflows.
- Plan migration away from unsafe SHA-crypt use where vendor-supported.
- Prioritize controls on public-facing authentication paths first.
Validation and detection
- Confirm whether sha256crypt or sha512crypt through 0.6 is used anywhere.
- Review public routes that hash user-supplied passwords.
- Verify maximum password length handling in authentication workflows.
- Monitor authentication endpoints for abnormal CPU consumption patterns.
- Document any compensating controls or vendor guidance found.
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.
Credential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2016-20013 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://twitter.com/solardiz/status/795601240151457793CVE reference · x_refsource_MISC
- https://pthree.org/2018/05/23/do-not-use-sha256crypt-sha512crypt-theyre-dangerous/CVE reference · x_refsource_MISC
- https://akkadia.org/drepper/SHA-crypt.txtCVE 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.