CVE-2026-55204

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 2026-06-18. 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-2026-37906 (ENISA EUVD) · GHSA-4vj2-5mvx-3vcc (GitHub Security Advisories)Source: ENISA EUVD

7.5EG
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).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

HAProxy through 3.4.0, fixed in commit 9a6d1fe, contains a null pointer dereference vulnerability in hpack_dht_insert() within src/hpack-tbl.c that fails to validate the return value of hpack_dht_defrag() when the memory pool is exhausted. An attacker can trigger HPACK dynamic table insertions under memory pressure to dereference a NULL pointer and crash HAProxy worker processes, causing denial of service.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100

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.
Exploitation0.5% × 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
0.5%
EPSS %ILE
41st
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
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-25). 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: 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.

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

June 18, 2026

Last Modified

October 26, 2026

Advisory Details (2)

Auto-updated Jun 18, 2026
Patch available. Sources: github_commit.
Web page

HAProxy - NULL Pointer Dereference in hpack_dht_insert Function | Advisories | VulnCheck

https://www.vulncheck.com/advisories/haproxy-null-pointer-dereference-in-hpack-dht-insert-function
GitHub commit

commit 9a6d1fe3f00d (haproxy/haproxy)

Fix landed in haproxy/haproxy commit 9a6d1fe3f00d — awaiting tagged release

https://github.com/haproxy/haproxy/commit/9a6d1fe3f00d86ab4ea6ea6ea0a5d48fc058a513

Patch Availability(20)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntuvim-haproxy (2.4.30-0ubuntu0.22.04.2) @ jammy2026-10-26ubuntu
redhatopenshift4/ose-haproxy-router-rhel9:17908553482026-10-15redhat
redhatopenshift4/ose-haproxy-router-rhel9:17908568912026-10-15redhat
redhatopenshift4/ose-haproxy-router-rhel9:17908549022026-10-15redhat
redhatopenshift4/ose-haproxy-router-rhel9:17899204412026-09-30redhat
redhatopenshift4/ose-haproxy-router-rhel9:17893791962026-09-22redhat
redhatopenshift4/ose-haproxy-router-rhel9:17894710432026-09-22redhat
redhatopenshift4/ose-haproxy-router-rhel9:17888883692026-09-15redhat
redhatrhui5/haproxy-rhel9:17888804562026-09-09redhat
redhathaproxy-0:3.0.5-6.el10_2.22026-08-17redhat
redhathaproxy-0:3.0.5-4.el10_0.32026-08-17redhat
redhathaproxy-0:2.4.22-3.el9_4.32026-08-17redhat
redhathaproxy-0:1.8.27-2.el8_4.22026-08-17redhat
redhathaproxy-0:1.8.27-5.el8_10.22026-08-17redhat
redhathaproxy-0:2.4.22-4.el9_6.32026-08-17redhat
redhathaproxy-0:1.8.27-4.el8_6.22026-08-17redhat
redhathaproxy-0:1.8.27-5.el8_8.22026-08-17redhat
redhathaproxy-0:2.8.14-3.el9_8.22026-08-17redhat
redhathaproxy-0:2.4.17-6.el9_2.52026-08-17redhat
redhathaproxy-main-3.0.25-0.1.hum12026-07-03redhat

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

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
haproxy2.2.16-1 ... 3.4.3-1 (180 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
haproxy2.6.12-1 ... 3.4.6-1 (105 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
haproxy3.0.11-1 ... 3.4.6-1 (58 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
haproxy3.0.11-1 ... 3.2.9-1 (31 versions)
  • every version up to 3.2.20-1: fixed in 3.2.20-1
—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

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 13× in last 7d / 48× 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 390 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 290 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  2. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  3. 2026-10-26 11:28 UTCEG score recompute
  4. 2026-10-26 11:28 UTCVendor advisory
  5. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  6. 2026-10-25 14:19 UTCEG score recompute
  7. 2026-10-24 17:39 UTCEG score recompute
  8. 2026-10-24 17:39 UTCVendor advisory
  9. 2026-10-24 17:39 UTCGHSA enrichmentGHSA-4vj2-5mvx-3vcc · GitHub severity HIGH · GitHub CVSS 7.5
  10. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  11. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  12. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  13. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  14. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  15. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  16. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  17. 2026-10-18 03:30 UTCEG score recompute
  18. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  19. 2026-10-17 03:27 UTCEG score recompute
  20. 2026-10-17 03:27 UTCVendor advisory
  21. 2026-10-17 03:26 UTCGHSA enrichmentGHSA-4vj2-5mvx-3vcc · GitHub severity HIGH · GitHub CVSS 7.5
  22. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  23. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  24. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  25. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 39th percentile
Show 75 more
  1. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  2. 2026-10-12 15:56 UTCEG score recompute
  3. 2026-10-11 19:39 UTCEG score recompute
  4. 2026-10-11 16:54 UTCEG score recompute
  5. 2026-10-11 14:17 UTCEG score recompute
  6. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  7. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  8. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  9. 2026-10-08 17:28 UTCEG score recompute
  10. 2026-10-08 17:28 UTCVendor advisory
  11. 2026-10-08 17:28 UTCGHSA enrichmentGHSA-4vj2-5mvx-3vcc · GitHub severity HIGH · GitHub CVSS 7.5
  12. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  13. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  14. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  15. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  16. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  17. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  18. 2026-10-03 04:39 UTCOSV refresh
  19. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  20. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  21. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  22. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  23. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  24. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  25. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  26. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  27. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  28. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  29. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  30. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  31. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  32. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  33. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  34. 2026-09-14 02:18 UTCEG score recompute
  35. 2026-09-14 02:18 UTCVendor advisory
  36. 2026-09-14 02:18 UTCGHSA enrichmentGHSA-4vj2-5mvx-3vcc · GitHub severity HIGH · GitHub CVSS 7.5
  37. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  38. 2026-09-13 13:53 UTCEG score recompute
  39. 2026-09-13 13:53 UTCVendor advisory
  40. 2026-09-13 13:53 UTCGHSA enrichmentGHSA-4vj2-5mvx-3vcc · GitHub severity HIGH · GitHub CVSS 7.5
  41. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  42. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  43. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  44. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  45. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  46. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  47. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  48. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  49. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  50. 2026-08-30 20:55 UTCEG score recompute
  51. 2026-08-30 20:55 UTCVendor advisory
  52. 2026-08-30 20:55 UTCGHSA enrichmentGHSA-4vj2-5mvx-3vcc · GitHub severity HIGH · GitHub CVSS 7.5
  53. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  54. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  55. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  56. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  57. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  58. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  59. 2026-08-25 02:29 UTCVendor advisory
  60. 2026-08-25 02:29 UTCGHSA enrichmentGHSA-4vj2-5mvx-3vcc · GitHub severity HIGH · GitHub CVSS 7.5
  61. 2026-08-24 15:02 UTCEG score recompute
  62. 2026-08-24 15:02 UTCVendor advisory
  63. 2026-08-24 15:02 UTCGHSA enrichmentGHSA-4vj2-5mvx-3vcc · GitHub severity HIGH · GitHub CVSS 7.5
  64. 2026-08-24 00:04 UTCVendor advisory
  65. 2026-08-24 00:03 UTCGHSA enrichmentGHSA-4vj2-5mvx-3vcc · GitHub severity HIGH · GitHub CVSS 7.5
  66. 2026-08-23 12:34 UTCVendor advisory
  67. 2026-08-23 12:34 UTCGHSA enrichmentGHSA-4vj2-5mvx-3vcc · GitHub severity HIGH · GitHub CVSS 7.5
  68. 2026-08-23 01:07 UTCEG score recompute
  69. 2026-08-23 01:07 UTCVendor advisory
  70. 2026-08-23 01:07 UTCGHSA enrichmentGHSA-4vj2-5mvx-3vcc · GitHub severity HIGH · GitHub CVSS 7.5
  71. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  72. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  73. 2026-08-21 18:49 UTCVendor advisory
  74. 2026-08-21 18:49 UTCGHSA enrichmentGHSA-4vj2-5mvx-3vcc · GitHub severity HIGH · GitHub CVSS 7.5
  75. 2026-08-21 07:22 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-55204?
CVE-2026-55204 is a high-severity vulnerability; its CVE record was published on June 18, 2026. HAProxy through 3.4.0, fixed in commit 9a6d1fe, contains a null pointer dereference vulnerability in hpackdhtinsert() within src/hpack-tbl.c that fails to validate the return value of hpackdhtdefrag() when the memory pool is exhausted. An attacker can trigger HPACK dynamic table insertions under…
When was CVE-2026-55204 made public?
CVE-2026-55204 was made public on June 16, 2026: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on June 18, 2026. EchelonGraph's copy of the record carries a last-modified date of October 26, 2026; the record at its source may have been updated since.
Is CVE-2026-55204 actively exploited?
CVE-2026-55204 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-2026-55204?
CVE-2026-55204 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-2026-55204?
A fix for CVE-2026-55204 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55204 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-55204

Explore →

Is Your Infrastructure Affected by CVE-2026-55204?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.