CVE-2026-18355

HIGHPre-NVD 7.57.5
EchelonGraph scoreMEDIUM confidence

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

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-09-07. A secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 4 sources updated this week

Also known asEUVD-2026-72455 (ENISA EUVD) · GHSA-r5vv-79fp-2427 (GitHub Security Advisories)Source: ENISA EUVD

7.5EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.8%CVSS: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

A heap buffer overflow flaw was found in the SASL I/O layer of 389 Directory Server (389-ds-base). In sasl_io_start_packet(), the wrapped-record length read from the wire is validated only against an upper bound. A small wire length (0, 1, or 2) produces an encrypted_buffer_count below the already-consumed encrypted_buffer_offset, causing an unsigned subtraction underflow in sasl_io_read_packet(). PR_Recv is then requested to read approximately 4 GiB into a 1024-byte heap buffer, resulting in a heap buffer overflow with attacker-controlled content. After a successful SASL bind with integrity protection (SSF > 0), a remote authenticated attacker can cause a denial of service or potentially achieve remote code execution. This flaw is distinct from CVE-2026-11774, whose fix only guards against upper-bound overflow.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
34
EG Risk 34/100

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)
Severity75% × 45%
Impact severity (EG Severity): CVSS 7.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.8% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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.
EPSS PROB
0.8%
EPSS %ILE
57th
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 (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.

EG Severity
7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.8% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-29). 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; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade 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; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (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 7, 2026

Last Modified

October 8, 2026

Advisory Details (2)

Auto-updated Sep 7, 2026
Patch available. Sources: redhat.
Red Hat

2509186 – (CVE-2026-18355) CVE-2026-18355 389-ds-base: 389-ds-base: heap buffer overflow via SASL wrapped-record length lower-bound underflow in sasl_io_start_packet()

https://bugzilla.redhat.com/show_bug.cgi?id=2509186
Red HatMentions a patch (unverified)

CVE-2026-18355 - 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-2026-18355

Patch Availability(17)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatredhat-ds:11-8060020260908152739.0ca98e7e2026-10-08redhat
redhat389-ds-base-0:3.2.0-10.el10_22026-09-08redhat
redhatredhat-ds:12-9020020260903155914.1674d5742026-09-08redhat
redhatredhat-ds:11-8100020260904171440.37ed7c032026-09-08redhat
redhat389-ds-base-0:3.0.6-21.el10_02026-09-08redhat
redhat389-ds:1.4-8080020260831180218.6dbb38032026-09-08redhat
redhatdirsrv/dirsrv-container-rhel10:17888517652026-09-08redhat
redhat389-ds:1.4-8040020260901171549.96015a922026-09-08redhat
redhat389-ds-base-0:2.6.1-24.el9_62026-09-08redhat
redhat389-ds-base-0:2.2.4-22.el9_22026-09-08redhat
redhat389-ds-base-0:1.3.11.1-15.el7_92026-09-08redhat
redhat389-ds:1.4-8060020260901145727.824efc522026-09-08redhat
redhatredhat-ds:12-9040020260903102623.1674d5742026-09-08redhat
redhat389-ds:1.4-8100020260904155442.25e700aa2026-09-08redhat
redhat389-ds-base-0:2.4.5-29.el9_42026-09-08redhat
redhat389-ds-base-0:2.8.0-10.el9_82026-09-08redhat
redhatredhat-ds:11-8080020260903102346.f969626e2026-09-08redhat

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

(2 across 2 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
389-ds-base2.3.1+dfsg1-1 ... 3.3.1-3 (18 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
389-ds-base3.1.2+dfsg1-1 ... 3.3.1-3 (8 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 10× in last 7d / 85× 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 249 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 149 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 16:44 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  2. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  3. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  4. 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  5. 2026-10-30 15:15 UTCEG score recompute
  6. 2026-10-30 15:15 UTCVendor advisory
  7. 2026-10-30 15:15 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  8. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  9. 2026-10-28 16:31 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  10. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  11. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  12. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  13. 2026-10-25 14:45 UTCEG score recompute
  14. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  15. 2026-10-24 04:33 UTCEG score recompute
  16. 2026-10-24 04:33 UTCVendor advisory
  17. 2026-10-24 04:33 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  18. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  19. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  20. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  21. 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  22. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.8% · 57th percentile
  23. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  24. 2026-10-18 03:59 UTCEG score recompute
  25. 2026-10-17 17:51 UTCEG score recompute
Show 75 more
  1. 2026-10-17 17:51 UTCVendor advisory
  2. 2026-10-17 17:51 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  3. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  4. 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  5. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  6. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  7. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  8. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  9. 2026-10-12 16:27 UTCEG score recompute
  10. 2026-10-11 20:07 UTCEG score recompute
  11. 2026-10-11 17:20 UTCEG score recompute
  12. 2026-10-11 14:52 UTCEG score recompute
  13. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  14. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  15. 2026-10-10 10:17 UTCVendor advisory
  16. 2026-10-10 10:17 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  17. 2026-10-09 22:42 UTCEG score recompute
  18. 2026-10-09 22:42 UTCVendor advisory
  19. 2026-10-09 22:42 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  20. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  21. 2026-10-09 02:59 UTCEG score recompute
  22. 2026-10-09 02:59 UTCVendor advisory
  23. 2026-10-09 02:58 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  24. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  25. 2026-10-08 15:24 UTCEG score recompute
  26. 2026-10-08 15:24 UTCVendor advisory
  27. 2026-10-08 15:24 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  28. 2026-10-08 14:56 UTCEG score recompute
  29. 2026-10-08 14:56 UTCVendor advisory
  30. 2026-10-08 14:56 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  31. 2026-10-08 10:18 UTCEG score recompute
  32. 2026-10-08 10:18 UTCVendor advisory
  33. 2026-10-08 10:18 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  34. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  35. 2026-10-07 22:37 UTCEG score recompute
  36. 2026-10-07 22:37 UTCVendor advisory
  37. 2026-10-07 22:37 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  38. 2026-10-07 10:45 UTCVendor advisory
  39. 2026-10-07 10:45 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  40. 2026-10-06 23:11 UTCEG score recompute
  41. 2026-10-06 23:11 UTCVendor advisory
  42. 2026-10-06 23:11 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  43. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  44. 2026-10-06 11:37 UTCVendor advisory
  45. 2026-10-06 11:37 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  46. 2026-10-06 00:01 UTCEG score recompute
  47. 2026-10-06 00:01 UTCVendor advisory
  48. 2026-10-06 00:01 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  49. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  50. 2026-10-05 11:35 UTCVendor advisory
  51. 2026-10-05 11:35 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  52. 2026-10-05 00:01 UTCEG score recompute
  53. 2026-10-05 00:01 UTCVendor advisory
  54. 2026-10-05 00:01 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  55. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  56. 2026-10-04 12:27 UTCVendor advisory
  57. 2026-10-04 12:27 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  58. 2026-10-04 00:52 UTCEG score recompute
  59. 2026-10-04 00:52 UTCVendor advisory
  60. 2026-10-04 00:52 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  61. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  62. 2026-10-03 13:07 UTCVendor advisory
  63. 2026-10-03 13:07 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  64. 2026-10-03 01:31 UTCEG score recompute
  65. 2026-10-03 01:31 UTCVendor advisory
  66. 2026-10-03 01:31 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  67. 2026-10-02 13:57 UTCVendor advisory
  68. 2026-10-02 13:57 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  69. 2026-10-02 02:00 UTCEG score recompute
  70. 2026-10-02 02:00 UTCVendor advisory
  71. 2026-10-02 02:00 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  72. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  73. 2026-10-01 14:26 UTCVendor advisory
  74. 2026-10-01 14:26 UTCGHSA enrichmentGHSA-r5vv-79fp-2427 · GitHub severity HIGH · GitHub CVSS 7.5
  75. 2026-10-01 02:52 UTCVendor advisory

Frequently asked(5)

What is CVE-2026-18355?
CVE-2026-18355 is a high-severity vulnerability; its CVE record was published on September 7, 2026. A heap buffer overflow flaw was found in the SASL I/O layer of 389 Directory Server (389-ds-base). In sasl_io_start_packet(), the wrapped-record length read from the wire is validated only against an upper bound. A small wire length (0, 1, or 2) produces an encrypted_buffer_count below the…
When was CVE-2026-18355 made public?
CVE-2026-18355 was made public on September 7, 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 7, 2026. EchelonGraph's copy of the record carries a last-modified date of October 8, 2026; the record at its source may have been updated since.
Is CVE-2026-18355 actively exploited?
CVE-2026-18355 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.8% probability of exploitation in the next 30 days (57th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-18355?
CVE-2026-18355 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-18355?
A fix for CVE-2026-18355 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-18355 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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