Security readout for executives and security teams
Plain-English summary
Gunicorn 19.4.5 could allow an attacker to make a server return arbitrary HTTP response headers because CRLF characters were not properly neutralized. That can undermine trust in responses and security controls that rely on headers. The source bundle says the issue was fixed in 19.5.0.
Executive priority
Prioritize remediation for internet-facing Python services using Gunicorn 19.4.5. This is not flagged as known exploited, but the fix is old and available, so remaining exposure usually indicates dependency hygiene risk.
Technical view
CVE-2018-1000164 is a CWE-113 header-splitting flaw in Gunicorn's process_headers function in gunicorn/http/wsgi.py. The documented result is attacker-controlled HTTP response headers. Public sources identify Gunicorn 19.4.5 and state the fix appears in 19.5.0; Debian and Ubuntu issued security updates.
Likely exposure
Exposure is most likely in legacy Python web deployments running Gunicorn 19.4.5 directly, in containers, or through Debian/Ubuntu packages. The CVE metadata does not provide complete affected CPEs, so version inventory is required.
Exploitation context
The bundle does not indicate active exploitation, and KEV is false. Public discussion and vendor advisories documented the vulnerability in 2018. Treat exploit status as unconfirmed unless internal telemetry or vendor intelligence shows otherwise.
Researcher notes
Evidence points to improper CRLF handling in process_headers. The known impact is arbitrary response headers; the bundle does not prove broader outcomes, CVSS, or active exploitation. Affected-product metadata is incomplete, so validation should rely on concrete version discovery.
Mitigation direction
- Upgrade Gunicorn to 19.5.0 or a later fixed release.
- Apply relevant Debian or Ubuntu security updates where Gunicorn is distro-managed.
- Rebuild and redeploy containers or virtual environments containing Gunicorn 19.4.5.
- Restart affected services after package or dependency updates.
- Check current vendor guidance if pinned dependencies block immediate upgrade.
Validation and detection
- Inventory production, staging, container, and CI images for Gunicorn 19.4.5.
- Confirm running services use the installed Gunicorn version, not only package metadata.
- Verify Debian or Ubuntu hosts include the referenced security update.
- Review dependency lockfiles for stale Gunicorn pins.
- Run safe regression tests for header handling after upgrade.
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-2018-1000164 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://epadillas.github.io/2018/04/02/http-header-splitting-in-gunicorn-19.4.5CVE reference · x_refsource_MISC
- [debian-lts-announce] 20180422 [SECURITY] [DLA 1357-1] gunicorn security updateCVE reference · mailing-list, x_refsource_MLIST
- https://github.com/benoitc/gunicorn/issues/1227CVE reference · x_refsource_MISC
- DSA-4186CVE reference · vendor-advisory, x_refsource_DEBIAN
- USN-4022-1CVE reference · vendor-advisory, x_refsource_UBUNTU
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.