zlib before 1.3.2 allows CPU consumption via crc32_combine64 and crc32_combine_gen64 because x2nmodp can do right shifts within a loop that has no termination condition.
CVE-2026-27171
This medium-severity CVE scores 5.5 under NVD CVSS v3. EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory enrichment pending alignment with NVD CVSS.
- 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
- 5.5
- EG Score
- 5.5(low)
- EG Risk
- 29(Track)EG Risk 29/100SSVC: 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 computedSeverity55% × 45%Exploitation0% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 12%
- KEV
- Not listed
Published
February 18, 2026
Last Modified
June 17, 2026
References (6)
- cve@mitrehttps://7asecurity.com/blog/2026/02/zlib-7asecurity-audit/
- cve@mitrehttps://7asecurity.com/reports/pentest-report-zlib-RC1.1.pdf
- cve@mitrehttps://github.com/madler/zlib/issues/904
- cve@mitrehttps://github.com/madler/zlib/releases/tag/v1.3.2
- cve@mitrehttps://ostif.org/zlib-audit-complete/
- 134c704f-9b21-4f2e-91b3-4a467353bcc0https://7asecurity.com/reports/pentest-report-zlib-RC1.1.pdf
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
All Vendor Advisories
(1)
Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.
Data Freshness Timeline
(refreshed 4× in last 7d / 4× 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.
- 2026-07-27 13:25 UTCEG score recompute
- 2026-07-27 13:25 UTCVendor advisory
- 2026-07-27 13:25 UTCGHSA enrichment
- 2026-07-27 13:25 UTCOSV refresh
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Frequently asked(5)
What is CVE-2026-27171?
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How do I remediate CVE-2026-27171?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-27171
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