CVE-2026-52767

HIGHPre-NVD 8.28.2
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This high-severity CVE scores 8.2 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (27th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Elevated
8.2EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 8.2Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

YesWiki is a wiki system written in PHP. From version 4.6.2 to before version 4.6.6, HttpSignatureService::verifySignature() checks the result of PHP's openssl_verify() with a loose boolean negation - if (!openssl_verify(...)) { throw ... }. PHP's openssl_verify has four possible return values: 1, 0, -1, and "false". The -1 row is the bypass: PHP's truthiness rules make -1 a truthy value, so !(-1) === false, the throw is skipped, and the controller proceeds to processActivity(). Any condition that makes OpenSSL's EVP_VerifyFinal() return -1 triggers the bypass. The reachable consequence is the controller silently treats a failed verification as success and processes the attacker's payload. This issue has been patched in version 4.6.6.

CVSS v3
8.2
EG Score
8.2HIGHmedium confidence
EG Risk
68
EG Risk 68/100

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 (value × EchelonGraph’s weight)
Severity82% × 45%
The EG Score, 8.2 of 10.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.4%
EPSS %ILE
27th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

July 9, 2026

Last Modified

September 8, 2026

Advisory Details (3)

Auto-updated Sep 4, 2026
Patch available. Sources: github_commit, github_release, github.
GitHub release Patch Available

v4.6.6

Patch available: YesWiki/yeswiki v4.6.6

https://github.com/YesWiki/yeswiki/releases/tag/v4.6.6
GitHub commit Patch Available

commit d1795e0301e1 (YesWiki/yeswiki)

Patch available: YesWiki/yeswiki v4.6.6 (contains commit d1795e0301e1)

https://github.com/YesWiki/yeswiki/commit/d1795e0301e1a1078f17b4b98f56fff70de2029e
GitHub advisoryMentions a patch (unverified)

Unauthenticated ActivityPub Signature-Verification Bypass via `!openssl_verify(...)` accepting `int(-1)` · Advisory · YesWiki/yeswiki · GitHub

https://github.com/YesWiki/yeswiki/security/advisories/GHSA-mv28-wj57-f57g

Vendor Advisories for CVE-2026-52767(1)

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

Affected Packages

(1 across 1 ecosystem)
Packagist(1)
PackageVulnerable rangeFix by version rangeDependents
yeswiki/yeswikiv4.6.2, v4.6.3, v4.6.4, v4.6.5
  • 4.6.2 up to 4.6.6: fixed in 4.6.6
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 33× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  3. 2026-10-12 15:58 UTCEG score recompute
  4. 2026-10-11 19:41 UTCEG score recompute
  5. 2026-10-11 16:56 UTCEG score recompute
  6. 2026-10-11 14:19 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  9. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  10. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  11. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  12. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  13. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  14. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  15. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  16. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  17. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  18. 2026-10-01 16:01 UTCEG score recompute
  19. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  20. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  21. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  22. 2026-09-28 10:26 UTCEG score recompute
  23. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  24. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  25. 2026-09-26 00:27 UTCEPSS rescoreEPSS 0.4% · 26th percentile
Show 25 more
  1. 2026-09-24 11:23 UTCEG score recompute
  2. 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  3. 2026-09-23 05:53 UTCEG score recompute
  4. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  5. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  6. 2026-09-18 05:35 UTCEG score recompute
  7. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  8. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  9. 2026-09-13 23:45 UTCEG score recompute
  10. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  11. 2026-09-12 15:06 UTCEG score recompute
  12. 2026-09-12 03:21 UTCEG score recompute
  13. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  14. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  15. 2026-09-08 22:54 UTCEG score recompute
  16. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  17. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  18. 2026-09-06 13:59 UTCEG score recompute
  19. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  20. 2026-09-05 22:30 UTCEG score recompute
  21. 2026-09-05 00:19 UTCEG score recompute
  22. 2026-07-30 11:22 UTCEG score recompute
  23. 2026-07-26 12:17 UTCEG score recompute
  24. 2026-07-23 03:19 UTCEG score recompute
  25. 2026-07-09 21:46 UTCEG score recompute

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Frequently asked(5)

What is CVE-2026-52767?
CVE-2026-52767 is a high-severity vulnerability; its CVE record was published on July 9, 2026. YesWiki is a wiki system written in PHP. From version 4.6.2 to before version 4.6.6, HttpSignatureService::verifySignature() checks the result of PHP's opensslverify() with a loose boolean negation - if (!opensslverify(...)) { throw ... }. PHP's opensslverify has four possible return values: 1, 0,…
When was the CVE record for CVE-2026-52767 published?
The CVE record for CVE-2026-52767 was published on July 9, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 8, 2026; the record at its source may have been updated since.
Is CVE-2026-52767 actively exploited?
CVE-2026-52767 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (27th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-52767?
CVE-2026-52767 has a CVSS base score of 8.2 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-52767?
A fix for CVE-2026-52767 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-52767 are linked in the Vendor Advisories panel on this page.

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