CVE-2026-88831

MEDIUMPre-NVD 5.35.3
EchelonGraph scoreMEDIUM confidence

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

Score 5.3 from GitHub Security Advisory published 2026-09-23. A secondary CVSS source baseline 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source

Also known asEUVD-2026-85509 (ENISA EUVD) · GHSA-w27x-jw4w-69xf (GitHub Security Advisories)Source: ENISA EUVD

5.3EG
EchelonGraph verdictMonitorRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 5.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

BusyBox httpd IP deny rules with invalid CIDR prefix lengths fail open, leaving a parsed IP with a zeroed mask so the rule matches no clients.

CVSS v3
5.3
EG Score
5.3MEDIUMmedium confidence
EG Risk
39
EG Risk 39/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity53% × 45%
Impact severity (EG Severity): CVSS 5.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.2% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
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 none (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
0.2%
EPSS %ILE
14th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (5.3): severity, escalated by confirmed exploitation. This CVE's 5.3 is its impact severity (EG Severity), not escalated.

EG Severity
5.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS. FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

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 none (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.

The score's inputs: 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

September 23, 2026

Last Modified

September 25, 2026

Advisory Details (2)

Auto-updated Sep 23, 2026
Patch available. Sources: redhat.
Red Hat

2531346 – (CVE-2026-88831) CVE-2026-88831 busybox: busybox: httpd silently fails open when IP deny rules contain invalid CIDR prefix lengths

https://bugzilla.redhat.com/show_bug.cgi?id=2531346
Red HatMentions a patch (unverified)

CVE-2026-88831 - Red Hat Customer Portal

Affected: Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to a

https://access.redhat.com/security/cve/CVE-2026-88831

Patch Availability(1)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatbusybox-main-1.37.0-9.1.hum12026-09-25redhat

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.

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
busybox1:1.35.0-4 ... 1:1.38.0-3 (28 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
busybox1:1.37.0-10 ... 1:1.38.0-3 (9 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
busybox1:1.37.0-10 ... 1:1.38.0-3 (9 versions)
  • every version on: no fix on record
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 66× 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.

Showing the most recent 100 of 109 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 9 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  2. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  3. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  4. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  5. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  6. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  7. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  8. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  9. 2026-10-25 13:53 UTCEG score recompute
  10. 2026-10-24 16:34 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  11. 2026-10-23 18:36 UTCEG score recompute
  12. 2026-10-23 18:36 UTCVendor advisory
  13. 2026-10-23 18:35 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  14. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  15. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  16. 2026-10-22 12:33 UTCEG score recompute
  17. 2026-10-22 12:33 UTCVendor advisory
  18. 2026-10-22 12:33 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  19. 2026-10-21 16:34 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  20. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  21. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  22. 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  23. 2026-10-18 03:03 UTCEG score recompute
  24. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  25. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.2% · 13th percentile
Show 75 more
  1. 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  2. 2026-10-14 16:34 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  3. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  4. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  5. 2026-10-12 14:49 UTCEG score recompute
  6. 2026-10-11 19:15 UTCEG score recompute
  7. 2026-10-11 16:32 UTCEG score recompute
  8. 2026-10-11 14:04 UTCEG score recompute
  9. 2026-10-11 14:04 UTCVendor advisory
  10. 2026-10-11 14:04 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  11. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  12. 2026-10-11 13:48 UTCEG score recompute
  13. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  14. 2026-10-10 16:09 UTCEG score recompute
  15. 2026-10-10 16:09 UTCVendor advisory
  16. 2026-10-10 16:08 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  17. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  18. 2026-10-09 18:10 UTCVendor advisory
  19. 2026-10-09 18:09 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  20. 2026-10-08 20:10 UTCEG score recompute
  21. 2026-10-08 20:10 UTCVendor advisory
  22. 2026-10-08 20:10 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  23. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  24. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  25. 2026-10-07 20:52 UTCVendor advisory
  26. 2026-10-07 20:52 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  27. 2026-10-06 22:44 UTCEG score recompute
  28. 2026-10-06 22:44 UTCVendor advisory
  29. 2026-10-06 22:44 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  30. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  31. 2026-10-06 00:49 UTCEG score recompute
  32. 2026-10-06 00:49 UTCVendor advisory
  33. 2026-10-06 00:49 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  34. 2026-10-05 17:44 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  35. 2026-10-05 02:53 UTCEG score recompute
  36. 2026-10-05 02:53 UTCVendor advisory
  37. 2026-10-05 02:52 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  38. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  39. 2026-10-04 04:52 UTCEG score recompute
  40. 2026-10-04 04:52 UTCVendor advisory
  41. 2026-10-04 04:51 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  42. 2026-10-03 06:56 UTCEG score recompute
  43. 2026-10-03 06:56 UTCVendor advisory
  44. 2026-10-03 06:56 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  45. 2026-10-02 09:00 UTCEG score recompute
  46. 2026-10-02 09:00 UTCVendor advisory
  47. 2026-10-02 09:00 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  48. 2026-10-01 19:51 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  49. 2026-10-01 11:03 UTCEG score recompute
  50. 2026-10-01 11:03 UTCVendor advisory
  51. 2026-10-01 11:02 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  52. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  53. 2026-09-30 13:06 UTCEG score recompute
  54. 2026-09-30 13:06 UTCVendor advisory
  55. 2026-09-30 13:06 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  56. 2026-09-29 15:05 UTCEG score recompute
  57. 2026-09-29 15:05 UTCVendor advisory
  58. 2026-09-29 15:05 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  59. 2026-09-28 17:10 UTCEG score recompute
  60. 2026-09-28 17:10 UTCVendor advisory
  61. 2026-09-28 17:09 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  62. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  63. 2026-09-27 19:14 UTCEG score recompute
  64. 2026-09-27 19:14 UTCVendor advisory
  65. 2026-09-27 19:14 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  66. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  67. 2026-09-26 21:18 UTCEG score recompute
  68. 2026-09-26 21:18 UTCVendor advisory
  69. 2026-09-26 21:18 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  70. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  71. 2026-09-25 23:22 UTCEG score recompute
  72. 2026-09-25 23:22 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  73. 2026-09-25 22:34 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  74. 2026-09-25 15:58 UTCGHSA enrichmentGHSA-w27x-jw4w-69xf · GitHub CVSS 5.3
  75. 2026-09-24 18:02 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-88831?
CVE-2026-88831 is a medium-severity vulnerability; its CVE record was published on September 23, 2026. BusyBox httpd IP deny rules with invalid CIDR prefix lengths fail open, leaving a parsed IP with a zeroed mask so the rule matches no clients.
When was CVE-2026-88831 made public?
CVE-2026-88831 was made public on September 23, 2026: that is the date its CVE record's CNA, Red Hat, Inc., gives for when the vulnerability was made public. The CVE record itself was published on September 23, 2026. EchelonGraph's copy of the record carries a last-modified date of September 25, 2026; the record at its source may have been updated since.
Is CVE-2026-88831 actively exploited?
CVE-2026-88831 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (14th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-88831?
CVE-2026-88831 has a CVSS base score of 5.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-88831?
A fix for CVE-2026-88831 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-88831 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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