CVE-2017-8923

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-14. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 7%CVSS: 9.8Exploit: None knownExposed: 0

A fix is available — apply it.

The zend_string_extend function in Zend/zend_string.h in PHP through 7.1.5 does not prevent changes to string objects that result in a negative length, which allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact by leveraging a script's use of .= with a long string.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
51(Track)
EG Risk 51/100SSVC: 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 computed
Severity98% × 45%
Exploitation7% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
7%
EPSS %ILE
94%
KEV
Not listed

Published

May 12, 2017

Last Modified

June 17, 2026

Advisory Details (3)

Auto-updated Jul 26, 2026
No patch confirmed yet.
generic

NetApp Product Security

https://security.netapp.com/advisory/ntap-20241227-0007/
generic

PHP :: Bug #74577 :: Memory corruption in zend_string_extend

https://bugs.php.net/bug.php?id=74577
generic
http://www.securityfocus.com/bid/98518

Vendor Advisories for CVE-2017-8923(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuphp7.0-snmp (7.0.33-0ubuntu0.16.04.16+esm3) @ xenial2026-05-20ubuntu
ubuntuphp7.4-opcache (7.4.3-4ubuntu2.10) @ focal2026-05-20ubuntu
ubuntuphp8.0-imap (8.0.8-1ubuntu0.3) @ impish2026-05-20ubuntu
redhatphp:7.4-8080020230118140634.cc3424242023-05-16redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(4)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 8× in last 7d / 43× 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.

Showing the most recent 100 of 129 total refreshes for this CVE.

  1. 2026-07-26 14:51 UTCEPSS rescore
  2. 2026-07-26 14:51 UTCEPSS rescore
  3. 2026-07-25 09:11 UTCOSV refresh
  4. 2026-07-23 14:15 UTCEPSS rescore
  5. 2026-07-23 01:31 UTCEG score recompute
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  1. 2026-07-09 19:06 UTCEPSS rescore
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  3. 2026-07-08 04:05 UTCOSV refresh
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  27. 2026-06-21 01:57 UTCEPSS rescore
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  29. 2026-06-19 15:55 UTCOSV refresh
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Frequently asked(5)

What is CVE-2017-8923?
CVE-2017-8923 is a critical vulnerability published on May 12, 2017. The zendstringextend function in Zend/zend_string.h in PHP through 7.1.5 does not prevent changes to string objects that result in a negative length, which allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact by leveraging a script's use…
When was CVE-2017-8923 disclosed?
CVE-2017-8923 was first published in the National Vulnerability Database on May 12, 2017, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2017-8923 actively exploited?
CVE-2017-8923 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 7% probability of exploitation in the next 30 days, which ranks it in the top 6.4% of all scored CVEs.
What is the CVSS score of CVE-2017-8923?
CVE-2017-8923 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2017-8923?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2017-8923, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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