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
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 7%CVSS: 9.8Exploit: NoneExposed: 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)
EPSS
93.6%
KEV
Not listed

Published

May 12, 2017

Last Modified

May 13, 2026

Advisory Details (3)

Auto-updated Jun 22, 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.

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 12× in last 7d / 41× 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 109 total refreshes for this CVE.

  1. 2026-07-07 13:42 UTCEPSS rescore
  2. 2026-07-06 16:24 UTCEPSS rescore
  3. 2026-07-06 16:24 UTCEPSS rescore
  4. 2026-07-06 02:20 UTCEPSS rescore
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  6. 2026-07-05 02:27 UTCEPSS rescore
  7. 2026-07-04 06:28 UTCEPSS rescore
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  9. 2026-07-02 16:54 UTCEPSS rescore
  10. 2026-07-01 15:03 UTCEPSS rescore
  11. 2026-06-30 23:19 UTCEPSS rescore
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  13. 2026-06-28 14:04 UTCEPSS rescore
  14. 2026-06-28 04:53 UTCEPSS rescore
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  16. 2026-06-27 03:06 UTCEPSS rescore
  17. 2026-06-25 13:47 UTCEPSS rescore
  18. 2026-06-24 14:02 UTCEPSS rescore
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  20. 2026-06-23 21:30 UTCEPSS rescore
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  24. 2026-06-21 01:57 UTCEPSS rescore
  25. 2026-06-21 01:57 UTCEPSS rescore
Show 75 more
  1. 2026-06-19 15:55 UTCOSV refresh
  2. 2026-06-18 17:50 UTCEPSS rescore
  3. 2026-06-17 17:50 UTCEPSS rescore
  4. 2026-06-16 17:50 UTCEPSS rescore
  5. 2026-06-15 17:45 UTCEPSS rescore
  6. 2026-06-14 23:14 UTCEPSS rescore
  7. 2026-06-14 23:14 UTCEPSS rescore
  8. 2026-06-13 22:58 UTCEPSS rescore
  9. 2026-06-13 22:57 UTCEPSS rescore
  10. 2026-06-12 23:09 UTCEPSS rescore
  11. 2026-06-12 23:09 UTCEPSS rescore
  12. 2026-06-11 13:57 UTCEPSS rescore
  13. 2026-06-10 22:15 UTCEPSS rescore
  14. 2026-06-10 13:19 UTCEPSS rescore
  15. 2026-06-08 14:14 UTCEPSS rescore
  16. 2026-06-08 14:14 UTCEPSS rescore
  17. 2026-06-07 15:22 UTCEPSS rescore
  18. 2026-06-07 15:22 UTCEPSS rescore
  19. 2026-06-05 22:44 UTCEPSS rescore
  20. 2026-06-05 22:44 UTCEPSS rescore
  21. 2026-06-05 06:08 UTCEPSS rescore
  22. 2026-06-05 06:08 UTCEPSS rescore
  23. 2026-06-04 13:10 UTCEPSS rescore
  24. 2026-06-04 13:10 UTCEPSS rescore
  25. 2026-06-02 20:11 UTCEPSS rescore
  26. 2026-06-02 20:11 UTCEPSS rescore
  27. 2026-05-31 22:28 UTCEPSS rescore
  28. 2026-05-31 00:14 UTCEPSS rescore
  29. 2026-05-31 00:14 UTCEPSS rescore
  30. 2026-05-30 22:23 UTCOSV refresh
  31. 2026-05-29 13:41 UTCEPSS rescore
  32. 2026-05-28 13:42 UTCEPSS rescore
  33. 2026-05-28 13:42 UTCEPSS rescore
  34. 2026-05-27 13:38 UTCEPSS rescore
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  36. 2026-05-26 13:42 UTCEPSS rescore
  37. 2026-05-26 07:17 UTCEPSS rescore
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  39. 2026-05-21 22:40 UTCEPSS rescore
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  41. 2026-05-20 22:37 UTCEPSS rescore
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  50. 2026-05-20 11:21 UTCEPSS rescore
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  55. 2026-05-20 11:21 UTCEPSS rescore
  56. 2026-05-20 08:51 UTCEG score recompute
  57. 2026-05-20 08:51 UTCVendor advisory
  58. 2026-05-20 08:51 UTCGHSA enrichment
  59. 2026-05-20 04:43 UTCEG score recompute
  60. 2026-05-20 04:43 UTCVendor advisory
  61. 2026-05-20 04:43 UTCGHSA enrichment
  62. 2026-05-20 00:35 UTCEG score recompute
  63. 2026-05-20 00:35 UTCVendor advisory
  64. 2026-05-20 00:35 UTCGHSA enrichment
  65. 2026-05-19 20:27 UTCEG score recompute
  66. 2026-05-19 20:27 UTCVendor advisory
  67. 2026-05-19 20:27 UTCGHSA enrichment
  68. 2026-05-19 16:19 UTCEG score recompute
  69. 2026-05-19 16:19 UTCVendor advisory
  70. 2026-05-19 16:19 UTCGHSA enrichment
  71. 2026-05-19 12:11 UTCEG score recompute
  72. 2026-05-19 12:11 UTCVendor advisory
  73. 2026-05-19 12:11 UTCGHSA enrichment
  74. 2026-05-19 08:03 UTCEG score recompute
  75. 2026-05-19 08:03 UTCVendor advisory

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 May 13, 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 93.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
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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