CVE-2026-10821

MEDIUMPre-NVD 6.66.6—
EchelonGraph scoreMEDIUM confidence

Score 6.6 from GitHub Security Advisory published 2026-09-02. A secondary CVSS source baseline 6.6; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this weekElevated
6.6EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 6.6Exploit: Elevated riskExposed services: Not assessed

No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.

The Yoast SEO Premium WordPress plugin before 27.6.1 does not sanitize control characters from redirect origins before writing them to the site's Apache configuration file when the file-based redirect mode is enabled, and the redirect-creation endpoint is reachable by users with only Author-level access. This allows such users to inject arbitrary newline-delimited Apache directives into the root .htaccess file. On Apache servers that honour PHP directives, the injection can be chained with the user's own media upload (a polyglot image carrying a PHP payload) and an auto_prepend_file directive to achieve Remote Code Execution.

CVSS v3
6.6
EG Score
6.6MEDIUMmedium confidence
EG Risk
46
EG Risk 46/100CISA SSVC

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
Severity66% × 45%
Exploitation40% × 40%
Automatability0% × 15%
CISA SSVC: Track at low, Track* at medium and Attend at high mission impact.
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.
EPSS PROB
0.5%
EPSS %ILE
41st
KEV
Not listed

CISA SSVCTrack at low, Track* at medium and Attend at high mission impact.

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 2, 2026

Last Modified

September 3, 2026

Advisory Details (2)

Auto-updated Sep 2, 2026
🔬 Proof of concept available. No fix on record yet.
generic

Yoast SEO Premium 27.6.1: additional security measures for redirect handling

https://yoast.com/yoast-seo-premium-may-26-2026/
generic🟡 PoC Available

Yoast SEO Premium < 27.6.1 – Author+ Arbitrary .htaccess Directive Injection to RCE | CVE 2026-10821 | Plugin Vulnerabilities

https://wpscan.com/vulnerability/2ddd8362-7248-48de-aab9-74c70e7d5dd6/

Vendor Advisories for CVE-2026-10821(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 18× in last 7d / 72× 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.

  1. 2026-10-10 19:59 UTCEPSS rescore
  2. 2026-10-10 03:35 UTCEG score recompute
  3. 2026-10-10 03:35 UTCGHSA enrichment
  4. 2026-10-09 20:06 UTCEPSS rescore
  5. 2026-10-09 01:43 UTCEG score recompute
  6. 2026-10-09 01:42 UTCGHSA enrichment
  7. 2026-10-08 17:11 UTCEPSS rescore
  8. 2026-10-07 23:47 UTCEPSS rescore
  9. 2026-10-07 23:46 UTCGHSA enrichment
  10. 2026-10-06 18:36 UTCEG score recompute
  11. 2026-10-06 18:36 UTCGHSA enrichment
  12. 2026-10-06 15:17 UTCEPSS rescore
  13. 2026-10-05 17:42 UTCEPSS rescore
  14. 2026-10-05 16:43 UTCEG score recompute
  15. 2026-10-05 16:43 UTCGHSA enrichment
  16. 2026-10-04 23:21 UTCEPSS rescore
  17. 2026-10-04 14:45 UTCEG score recompute
  18. 2026-10-04 14:45 UTCGHSA enrichment
  19. 2026-10-03 14:25 UTCEPSS rescore
  20. 2026-10-03 12:54 UTCEG score recompute
  21. 2026-10-03 12:54 UTCGHSA enrichment
  22. 2026-10-02 07:04 UTCEG score recompute
  23. 2026-10-02 07:03 UTCGHSA enrichment
  24. 2026-10-01 19:49 UTCEPSS rescore
  25. 2026-10-01 05:13 UTCEG score recompute
Show 72 more
  1. 2026-10-01 05:13 UTCGHSA enrichment
  2. 2026-09-30 15:02 UTCEPSS rescore
  3. 2026-09-30 03:07 UTCEG score recompute
  4. 2026-09-30 03:07 UTCGHSA enrichment
  5. 2026-09-29 15:20 UTCEPSS rescore
  6. 2026-09-28 16:19 UTCEG score recompute
  7. 2026-09-28 16:19 UTCGHSA enrichment
  8. 2026-09-28 13:50 UTCEPSS rescore
  9. 2026-09-27 14:18 UTCEG score recompute
  10. 2026-09-27 14:18 UTCGHSA enrichment
  11. 2026-09-26 15:58 UTCEPSS rescore
  12. 2026-09-26 12:28 UTCEG score recompute
  13. 2026-09-26 12:28 UTCGHSA enrichment
  14. 2026-09-25 09:32 UTCEG score recompute
  15. 2026-09-25 09:32 UTCGHSA enrichment
  16. 2026-09-24 07:41 UTCEG score recompute
  17. 2026-09-24 07:41 UTCGHSA enrichment
  18. 2026-09-23 13:47 UTCEPSS rescore
  19. 2026-09-23 05:51 UTCEG score recompute
  20. 2026-09-23 05:51 UTCGHSA enrichment
  21. 2026-09-22 04:01 UTCEG score recompute
  22. 2026-09-22 04:01 UTCGHSA enrichment
  23. 2026-09-21 02:10 UTCEG score recompute
  24. 2026-09-21 02:10 UTCGHSA enrichment
  25. 2026-09-20 20:15 UTCEPSS rescore
  26. 2026-09-20 00:19 UTCEG score recompute
  27. 2026-09-20 00:19 UTCGHSA enrichment
  28. 2026-09-18 22:28 UTCEG score recompute
  29. 2026-09-18 22:28 UTCGHSA enrichment
  30. 2026-09-18 19:27 UTCEPSS rescore
  31. 2026-09-17 20:38 UTCEG score recompute
  32. 2026-09-17 20:38 UTCGHSA enrichment
  33. 2026-09-16 18:36 UTCEG score recompute
  34. 2026-09-16 18:36 UTCGHSA enrichment
  35. 2026-09-16 05:14 UTCEPSS rescore
  36. 2026-09-15 14:30 UTCEG score recompute
  37. 2026-09-15 14:30 UTCGHSA enrichment
  38. 2026-09-14 12:39 UTCEG score recompute
  39. 2026-09-14 12:39 UTCGHSA enrichment
  40. 2026-09-13 16:46 UTCEPSS rescore
  41. 2026-09-13 10:47 UTCEG score recompute
  42. 2026-09-13 10:47 UTCGHSA enrichment
  43. 2026-09-12 15:00 UTCEPSS rescore
  44. 2026-09-12 08:56 UTCEG score recompute
  45. 2026-09-12 08:56 UTCGHSA enrichment
  46. 2026-09-11 14:52 UTCEPSS rescore
  47. 2026-09-11 09:36 UTCEPSS rescore
  48. 2026-09-11 07:06 UTCEG score recompute
  49. 2026-09-11 07:06 UTCGHSA enrichment
  50. 2026-09-10 09:34 UTCEPSS rescore
  51. 2026-09-10 05:15 UTCGHSA enrichment
  52. 2026-09-09 03:25 UTCEG score recompute
  53. 2026-09-09 03:25 UTCGHSA enrichment
  54. 2026-09-08 22:00 UTCEPSS rescore
  55. 2026-09-08 01:32 UTCEG score recompute
  56. 2026-09-08 01:32 UTCGHSA enrichment
  57. 2026-09-07 16:01 UTCEPSS rescore
  58. 2026-09-06 23:41 UTCEG score recompute
  59. 2026-09-06 23:41 UTCGHSA enrichment
  60. 2026-09-06 13:47 UTCEPSS rescore
  61. 2026-09-05 21:49 UTCEG score recompute
  62. 2026-09-05 21:48 UTCGHSA enrichment
  63. 2026-09-04 19:58 UTCEG score recompute
  64. 2026-09-04 19:58 UTCGHSA enrichment
  65. 2026-09-04 05:06 UTCEPSS rescore
  66. 2026-09-03 18:04 UTCGHSA enrichment
  67. 2026-09-03 17:22 UTCEG score recompute
  68. 2026-09-03 17:22 UTCGHSA enrichment
  69. 2026-09-02 15:31 UTCEG score recompute
  70. 2026-09-02 15:09 UTCEG score recompute
  71. 2026-09-02 14:31 UTCEG score recompute
  72. 2026-09-02 14:26 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-10821?
CVE-2026-10821 is a medium vulnerability published on September 2, 2026. The Yoast SEO Premium WordPress plugin before 27.6.1 does not sanitize control characters from redirect origins before writing them to the site's Apache configuration file when the file-based redirect mode is enabled, and the redirect-creation endpoint is reachable by users with only Author-level…
When was CVE-2026-10821 disclosed?
CVE-2026-10821 was first published on September 2, 2026, with the most recent update on September 3, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-10821 actively exploited?
CVE-2026-10821 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (41st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-10821?
CVE-2026-10821 has a CVSS base score of 6.6 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-10821?
No fix for CVE-2026-10821 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The vendor advisories EchelonGraph has for CVE-2026-10821 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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