CVE-2026-27171Disclosure(zlib / zlib)

LOWCVSS 5.5 · MEDIUM

Signal is active with 1 mentions in latest observed window

Immediate actions

Patch zlib zlib systems immediately

Recommended action window: Monitor and triage in normal cycle

NVD description

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.

zlib CVEs Back to dashboard

0.5/ 10 priority

Sources & remediation

Exploit / PoC references

https://github.com/madler/zlib/issues/904

Other references

Weakness type (CWE)

CWE-1284

Priority

LOW

Exploitation

NONE

PoC

YES

Patch

AVAILABLE

Momentum

STABLE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

zlib

Threat summary

Patch or workaround signal is available
5 mentions across 3 observed days
Momentum state: stable

What's happening

Patch or workaround mentioned in 2 signals
Technical details provided in 4 signals
Disclosure: 2 classified signals
General: 2 classified signals
Peaked 2d ago at 3 mentions (2026-02-18); latest day: 1
5 total mentions across 3 days

Affected systems

Vendors

zlib

Products

zlib

Deep dive

Activity timeline5 mentions / 3d

Signal classification3 categories

Disclosure

240.0%

General

240.0%

Patch

120.0%

Referenced assets5 URLs

By indicator

Classification over time

Date	Total	Labels

2026-02-18	3	Disclosure1General2
2026-03-15	1	Disclosure1
2026-05-22	1	Patch1

Full discourse5 posts

Pete Massiello@petem59141d
Patch
Zlib for IBM i, while not utilized by every shop, presents a significant vulnerability that warrants attention. Vulnerability Details: - **CVEID:** CVE-2026-27171 - **Description:** Zlib versions prior to 1.3.2 allow for increased CPU consumption through the functions crc32_combine64 and crc32_combine_gen64. This occurs because x2nmodp can perform right shifts within a loop that lacks a termination condition. - **CWE:** CWE-1284: Improper Validation of Specified Quantity in Input - **CVSS Source:** NVD - **CVSS Base Score:** 5.5 - **CVSS Vector:** (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) Remediation/Fixes: **IBM i Release PTF Number(s):** - 7.6: SJ09728 - 7.5: SJ09726 - 7.4: SJ09723 - 7.3: SJ09723 It is crucial for users to apply the necessary patches to mitigate this vulnerability.
Post summary
IBM i users should apply the provided PTF patches (SJ09728, SJ09726, SJ09723) to mitigate CVE‑2026‑27171, a vulnerability with a CVSS score of 5.5 that allows high CPU consumption.
00020107
1.4K followersView on X
PurpleOps@PurpleOps_io209d
Disclosure
📢 𝐍𝐞𝐰 𝐂𝐕𝐄 𝐚𝐧𝐚𝐥𝐲𝐬𝐢𝐬 𝐣𝐮𝐬𝐭 𝐝𝐫𝐨𝐩𝐩𝐞𝐝! Explore the CVE-2026-27171 RCE flaw, its impact on Windows SMB, and practical steps to patch and defend your network for operational resilience. 🔗 Read the full breakdown → https://www.purple-ops.io/cybersecurity-threat-intelligence-blog/cve-2026-27171-rce-analysis/ What’s your take? Share with us!
Post summary
The post announces an analysis of CVE‑2026‑27171, describing it as an RCE flaw in Windows SMB with general patching guidance, but offers no proof‑of‑concept, exploit code, or evidence of active exploitation.
0000043
89 followersView on X
CVEarity@CVEarity234d
General
⚡ New CVE Alert: CVE-2026-27171 📊 Severity: 2.9 🚨 Risk Level: Low 🧩 Affects: Multiple / Unspecified Products Reference: https://nvd.nist.gov/vuln/detail/CVE-2026-27171 #CVE-2026-27171 #CVE #Low #CyberSecurity #InfoSec https://t.co/kTDOCTtjtB
Post summary
The tweet merely announces the CVE‑2026‑27171 with a low severity score and minimal detail, providing no actionable information.
0000044
56 followersView on X
Vulmon Vulnerability Feed@VulmonFeeds234d
Disclosure
CVE-2026-27171 zlib CPU Consumption Vulnerability via Infinite Loop in CRC32 Combine Fu... https://vulmon.com/vulnerabilitydetails?qid=CVE-2026-27171 Vulnerability Notification: https://alerts.vulmon.com/?utm_source=twitter&utm_medium=social&utm_campaign=2102281&utm_content=3
Post summary
A new CVE (CVE-2026-27171) has been announced, detailing a CPU consumption vulnerability in zlib caused by an infinite loop in the CRC32 Combine function.
0000080
4.0K followersView on X
CVE@CVEnew234d
General
CVE-2026-27171 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 conditi… https://www.cve.org/CVERecord?id=CVE-2026-27171
Post summary
The post references CVE-2026-27171 in zlib, noting a CPU exhaustion vulnerability in crc32_combine64 and crc32_combine_gen64 due to a loop with no termination condition, but provides no information about PoC, exploits, active use, or mitigation.
00000272
56.4K followersView on X

CPE platform detail1 entries

Part:

Vendor:

Product:

Version:

Target SW:

Target HW:

1 of 1 entries

Part	Vendor	Product	Version	Target SW	Target HW
App	zlib	zlib	-	-	-

Explore more

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What researchers are saying

CVE-2026-27171

Pete Massiello[verified]@petem59Patch

IBM i users should apply the provided PTF patches (SJ09728, SJ09726, SJ09723) to mitigate CVE‑2026‑27171, a vulnerability with a CVSS score of 5.5 that allows high CPU consumption.

PurpleOps[verified]@PurpleOps_ioDisclosure

The post announces an analysis of CVE‑2026‑27171, describing it as an RCE flaw in Windows SMB with general patching guidance, but offers no proof‑of‑concept, exploit code, or evidence of active exploitation.

CVEarity@CVEarityGeneral

The tweet merely announces the CVE‑2026‑27171 with a low severity score and minimal detail, providing no actionable information.

Vulmon Vulnerability Feed@VulmonFeedsDisclosure

A new CVE (CVE-2026-27171) has been announced, detailing a CPU consumption vulnerability in zlib caused by an infinite loop in the CRC32 Combine function.

CVE@CVEnewGeneral

The post references CVE-2026-27171 in zlib, noting a CPU exhaustion vulnerability in crc32_combine64 and crc32_combine_gen64 due to a loop with no termination condition, but provides no information about PoC, exploits, active use, or mitigation.