CVE-2020-11100

HIGHNVD 8.88.9▲
EchelonGraph scoreHIGH confidence

Score elevated to 8.9 because EPSS predicts 61% probability of exploitation within the next 30 days (top 0.9% of all CVEs). NVD baseline CVSS 8.8 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, ghsa, nvd
Elevated
8.9EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 61%
CISA-KEV: Not listedEPSS PROB: 61%CVSS: 8.8Exploit: Elevated riskExposed: 0

A fix is available — apply it.

In hpack_dht_insert in hpack-tbl.c in the HPACK decoder in HAProxy 1.8 through 2.x before 2.1.4, a remote attacker can write arbitrary bytes around a certain location on the heap via a crafted HTTP/2 request, possibly causing remote code execution.

CVSS v3
8.8
EG Score
8.9(high)
EG Risk
69(Track)
EG Risk 69/100SSVC: Track

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
Severity89% × 45%
Exploitation61% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
61%
EPSS %ILE
99%
KEV
Not listed

Published

April 2, 2020

Last Modified

November 21, 2024

Advisory Details (7)

Auto-updated Aug 21, 2026
Patch available. Sources: redhat.
generic

HAProxy: Arbitrary code execution (GLSA 202012-22) — Gentoo security

https://security.gentoo.org/glsa/202012-22
generic

[SECURITY] Fedora 30 Update: haproxy-1.8.25-1.fc30 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MNW5RZLIX7LOXRLV7WMHX22CI43XSXKW/
generic

[SECURITY] Fedora 31 Update: haproxy-2.0.14-1.fc31 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/264C7UL3X7L7QE74ZJ557IOUFS3J4QQC/
generic

[SECURITY] [DSA 4649-1] haproxy security update

https://lists.debian.org/debian-security-announce/2020/msg00052.html
generic

Making sure you're not a bot!

https://bugzilla.suse.com/show_bug.cgi?id=1168023
redhat Patch Available

1819111 – (CVE-2020-11100) CVE-2020-11100 haproxy: malformed HTTP/2 requests can lead to out-of-bounds writes

Affected: Red Hat Enterprise Linux 6 and 7 do not contain support for HTTP/2; therefore, they are not affected by this flaw.

https://bugzilla.redhat.com/show_bug.cgi?id=1819111
generic

HAProxy - The Reliable, High Perf. TCP/HTTP Load Balancer

http://www.haproxy.org

Vendor Advisories for CVE-2020-11100(5)

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

Patch Availability(6)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuvim-haproxy (2.0.5-1ubuntu0.4) @ eoan2026-05-27ubuntu
redhathaproxy-0:2.0.13-3.el72020-05-04redhat
redhathaproxy-0:1.8.23-3.el72020-04-07redhat
redhathaproxy-0:1.8.15-6.el8_1.12020-04-02redhat
redhathaproxy-0:1.8.15-5.el8_0.12020-04-02redhat
redhatrh-haproxy18-haproxy-0:1.8.17-1.el7.12020-04-02redhat

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

(21 across 21 ecosystems)
Alpine:v3.10(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.0.14-r0—
Alpine:v3.11(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.0.14-r0—
Alpine:v3.12(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.1.4-r0—
Alpine:v3.13(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.1.4-r0—
Alpine:v3.14(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.1.4-r0—
Alpine:v3.15(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.1.4-r0—
Alpine:v3.16(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.1.4-r0—
Alpine:v3.17(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.1.4-r0—
Alpine:v3.18(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.1.4-r0—
Alpine:v3.19(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.1.4-r0—
Alpine:v3.20(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.1.4-r0—
Alpine:v3.21(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.1.4-r0—
Alpine:v3.22(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.1.4-r0—
Alpine:v3.23(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.1.4-r0—
Alpine:v3.24(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.1.4-r0—
Alpine:v3.9(1)
PackageVulnerable rangeFixed inDependents
haproxy—1.8.25-r0—
Debian:10(1)
PackageVulnerable rangeFixed inDependents
haproxy1.8.19-1, 1.8.19-1+deb10u1, 1.8.19-1+deb10u2~bpo9+11.8.19-1+deb10u2—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.0.13-2—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.0.13-2—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.0.13-2—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
haproxy—2.0.13-2—

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 5× in last 7d / 18× 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.

Showing the most recent 100 of 117 total refreshes for this CVE.

  1. 2026-09-18 19:23 UTCEPSS rescore
  2. 2026-09-17 19:22 UTCEPSS rescore
  3. 2026-09-16 14:04 UTCEPSS rescore
  4. 2026-09-16 14:04 UTCEPSS rescore
  5. 2026-09-15 03:06 UTCEPSS rescore
  6. 2026-09-12 14:56 UTCEPSS rescore
  7. 2026-09-11 09:32 UTCEPSS rescore
  8. 2026-09-07 15:53 UTCOSV refresh
  9. 2026-09-06 13:44 UTCEPSS rescore
  10. 2026-09-05 15:24 UTCEPSS rescore
  11. 2026-09-04 13:56 UTCEPSS rescore
  12. 2026-09-02 14:08 UTCEPSS rescore
  13. 2026-08-30 19:14 UTCEPSS rescore
  14. 2026-08-30 01:18 UTCEPSS rescore
  15. 2026-08-28 21:37 UTCEPSS rescore
  16. 2026-08-26 14:42 UTCEPSS rescore
  17. 2026-08-21 01:09 UTCOSV refresh
  18. 2026-08-20 22:51 UTCEPSS rescore
  19. 2026-08-19 17:00 UTCEPSS rescore
  20. 2026-08-18 13:44 UTCEPSS rescore
  21. 2026-08-17 13:43 UTCEPSS rescore
  22. 2026-08-16 02:11 UTCEPSS rescore
  23. 2026-08-15 01:26 UTCEPSS rescore
  24. 2026-08-13 21:57 UTCEPSS rescore
  25. 2026-08-12 13:47 UTCEPSS rescore
Show 75 more
  1. 2026-08-07 16:23 UTCEPSS rescore
  2. 2026-08-05 19:14 UTCEPSS rescore
  3. 2026-08-05 16:40 UTCOSV refresh
  4. 2026-08-04 15:06 UTCEPSS rescore
  5. 2026-08-02 02:23 UTCEPSS rescore
  6. 2026-08-01 04:12 UTCEPSS rescore
  7. 2026-07-30 16:24 UTCEPSS rescore
  8. 2026-07-30 01:27 UTCEPSS rescore
  9. 2026-07-28 15:32 UTCEPSS rescore
  10. 2026-07-26 14:51 UTCEPSS rescore
  11. 2026-07-25 14:14 UTCEPSS rescore
  12. 2026-07-24 14:14 UTCEPSS rescore
  13. 2026-07-23 14:15 UTCEPSS rescore
  14. 2026-07-23 14:15 UTCEPSS rescore
  15. 2026-07-23 01:48 UTCEG score recompute▲ 0.10
  16. 2026-07-22 22:32 UTCEG score recompute
  17. 2026-07-22 14:05 UTCEPSS rescore
  18. 2026-07-21 15:22 UTCEPSS rescore
  19. 2026-07-21 15:22 UTCEPSS rescore
  20. 2026-07-20 17:04 UTCEPSS rescore
  21. 2026-07-19 14:59 UTCOSV refresh
  22. 2026-07-19 14:28 UTCEPSS rescore
  23. 2026-07-19 14:28 UTCEPSS rescore
  24. 2026-07-18 10:02 UTCEPSS rescore
  25. 2026-07-16 16:59 UTCEPSS rescore
  26. 2026-07-16 16:59 UTCEPSS rescore
  27. 2026-07-15 16:55 UTCEPSS rescore
  28. 2026-07-13 22:27 UTCEPSS rescore
  29. 2026-07-13 06:10 UTCEPSS rescore
  30. 2026-07-13 06:10 UTCEPSS rescore
  31. 2026-07-12 05:44 UTCEPSS rescore
  32. 2026-07-11 08:24 UTCEPSS rescore
  33. 2026-07-09 19:06 UTCEPSS rescore
  34. 2026-07-06 16:25 UTCEPSS rescore
  35. 2026-07-06 16:25 UTCEPSS rescore
  36. 2026-07-05 02:27 UTCEPSS rescore
  37. 2026-07-02 02:47 UTCOSV refresh
  38. 2026-07-01 15:03 UTCEPSS rescore
  39. 2026-07-01 15:03 UTCEPSS rescore
  40. 2026-06-30 23:20 UTCEPSS rescore
  41. 2026-06-30 23:20 UTCEPSS rescore
  42. 2026-06-28 04:54 UTCEPSS rescore
  43. 2026-06-28 04:54 UTCEPSS rescore
  44. 2026-06-27 03:06 UTCEPSS rescore
  45. 2026-06-25 13:47 UTCEPSS rescore
  46. 2026-06-25 13:47 UTCEPSS rescore
  47. 2026-06-23 21:31 UTCEPSS rescore
  48. 2026-06-23 21:31 UTCEPSS rescore
  49. 2026-06-22 14:23 UTCEPSS rescore
  50. 2026-06-22 14:23 UTCEPSS rescore
  51. 2026-06-21 01:57 UTCEPSS rescore
  52. 2026-06-21 01:57 UTCEPSS rescore
  53. 2026-06-18 17:50 UTCEPSS rescore
  54. 2026-06-18 17:50 UTCEPSS rescore
  55. 2026-06-17 17:50 UTCEPSS rescore
  56. 2026-06-17 17:50 UTCEPSS rescore
  57. 2026-06-16 17:50 UTCEPSS rescore
  58. 2026-06-16 17:50 UTCEPSS rescore
  59. 2026-06-15 17:46 UTCEPSS rescore
  60. 2026-06-14 05:43 UTCOSV refresh
  61. 2026-06-13 22:58 UTCEPSS rescore
  62. 2026-06-13 22:58 UTCEPSS rescore
  63. 2026-06-12 23:09 UTCEPSS rescore
  64. 2026-06-11 13:58 UTCEPSS rescore
  65. 2026-06-10 22:16 UTCEPSS rescore
  66. 2026-06-10 22:16 UTCEPSS rescore
  67. 2026-06-10 13:20 UTCEPSS rescore
  68. 2026-06-08 14:15 UTCEPSS rescore
  69. 2026-06-08 14:15 UTCEPSS rescore
  70. 2026-06-07 15:23 UTCEPSS rescore
  71. 2026-06-07 15:23 UTCEPSS rescore
  72. 2026-06-05 22:45 UTCEPSS rescore
  73. 2026-06-05 22:45 UTCEPSS rescore
  74. 2026-06-05 06:08 UTCEPSS rescore
  75. 2026-06-02 20:11 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2020-11100?
CVE-2020-11100 is a high vulnerability published on April 2, 2020. In hpackdhtinsert in hpack-tbl.c in the HPACK decoder in HAProxy 1.8 through 2.x before 2.1.4, a remote attacker can write arbitrary bytes around a certain location on the heap via a crafted HTTP/2 request, possibly causing remote code execution.
When was CVE-2020-11100 disclosed?
CVE-2020-11100 was first published in the National Vulnerability Database on April 2, 2020, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-11100 actively exploited?
CVE-2020-11100 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 61% probability of exploitation in the next 30 days, which ranks it in the top 0.9% of all scored CVEs.
What is the CVSS score of CVE-2020-11100?
CVE-2020-11100 has a CVSS v3 base score of 8.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.9.
How do I remediate CVE-2020-11100?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-11100, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2020-11100

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