CVE-2026-27171

Exp

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.

Published: 2026-02-18 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-27171 is rated Exploit Available (50/100): CVSS Low severity, with low exploitation likelihood (EPSS 0.20%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-27171

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-27171

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.01% 0.20% +0.20%
2 2026-02-18 — 0.01% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-27171

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
2.9 3.1 LOW
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 1.4 1.4 [email protected]
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 3.6 [email protected]

Weakness enumeration for CVE-2026-27171

OS Trackers for CVE-2026-27171

vendor priority summary link
alpine — CVE-2026-27171: 1 source package rows (zlib); 28 state rows across 6 repos (3.19-main, 3.20-main, 3.21-main, 3.22-main, 3.23-main, edge-main); fixed 5, open 23. https://security.alpinelinux.org/vuln/CVE-2026-27171
debian not yet assigned CVE-2026-27171 not yet assigned priority: Debian including 1 source packages (zlib), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-27171
redhat low — https://access.redhat.com/security/cve/CVE-2026-27171
suse medium CVE-2026-27171 severity moderate: SUSE including 276 source package names (1.1.1-1.36:libz1-1.2.13-150500.4.6.1, 1.1.1-1.39:libz1-1.2.13-150500.4.6.1, …), 446 product×package rows across 111 product lines (Container private-registry/harbor-core, Container private-registry/harbor-exporter, … (111 product lines)): Known Affected 231, Fixed 132, Known Not Affected 76, First Fixed 7. https://www.suse.com/security/cve/CVE-2026-27171/
ubuntu low CVE-2026-27171 low priority: Ubuntu including 4 source packages (klibc, rsync, zlib, zsync), 31 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): needs-triage 24, not-affected 4, needed 3. https://ubuntu.com/security/CVE-2026-27171

Affected software / configurations for CVE-2026-27171

Vendor Product Version Raw CPE
zlib zlib >= 1.2.12, < 1.3.2 cpe:2.3:a:zlib:zlib:*:*:*:*:*:*:*:*

References for CVE-2026-27171

cvelogic Threat Intelligence