CVE-2020-1967

HIGHNVD 7.58.1▲
EchelonGraph scoreHIGH confidence

Score elevated to 8.1 because EPSS predicts 53% probability of exploitation within the next 30 days (98th percentile of EPSS-scored CVEs). NVD baseline CVSS 7.5 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction (continuous uplift above 30%)
Sources: epss, nvd
Elevated
8.1EG
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 53%
CISA-KEV: Not listedEPSS PROB: 53%CVSS: 7.5Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

Server or client applications that call the SSL_check_chain() function during or after a TLS 1.3 handshake may crash due to a NULL pointer dereference as a result of incorrect handling of the "signature_algorithms_cert" TLS extension. The crash occurs if an invalid or unrecognised signature algorithm is received from the peer. This could be exploited by a malicious peer in a Denial of Service attack. OpenSSL version 1.1.1d, 1.1.1e, and 1.1.1f are affected by this issue. This issue did not affect OpenSSL versions prior to 1.1.1d. Fixed in OpenSSL 1.1.1g (Affected 1.1.1d-1.1.1f).

CVSS v3
7.5
EG Score
8.1HIGHhigh confidence
EG Risk
73
EG Risk 73/100CISA 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
Severity81% × 45%
Exploitation53% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
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
53%
EPSS %ILE
98th
KEV
Not listed

CISA SSVCTrack 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). 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

April 21, 2020

Last Modified

October 8, 2026

Advisory Details (6)

Auto-updated Oct 8, 2026
🔬 Proof of concept available. Patch available.
generic

Pony Mail

https://lists.apache.org/thread.html/r94d6ac3f010a38fccf4f432b12180a13fa1cf303559bd805648c9064%40%3Cdev.tomcat.apache.org%3E
generic

Pony Mail

https://lists.apache.org/thread.html/r66ea9c436da150683432db5fbc8beb8ae01886c6459ac30c2cea7345%40%3Cdev.tomcat.apache.org%3E
generic🟡 PoC Available

GitHub - irsl/CVE-2020-1967: Proof of concept exploit about OpenSSL signature_algorithms_cert DoS flaw (CVE-2020-1967) · GitHub

https://github.com/irsl/CVE-2020-1967
generic

oss-security - [CVE-2020-1967] OpenSSL 1.1.1d+ Segmentation fault in SSL_check_chain

http://www.openwall.com/lists/oss-security/2020/04/22/2
generic🟡 PoC Available

Full Disclosure: CVE-2020-1967: proving sigalg != NULL

http://seclists.org/fulldisclosure/2020/May/5
generic

Packet Storm

http://packetstormsecurity.com/files/157527/OpenSSL-signature_algorithms_cert-Denial-Of-Service.html

Affected Packages

(24 across 22 ecosystems)
Alpine:v3.15(2)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
openssl3—
  • every version up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.16(2)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
openssl3—
  • every version up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.10(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.11(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.12(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.13(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.14(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.17(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.18(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.19(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.20(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.21(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.22(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
Alpine:v3.9(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • 1.1.1d up to 1.1.1g-r0: fixed in 1.1.1g-r0
—
crates.io(1)
PackageVulnerable rangeFix by version rangeDependents
openssl-src—
  • 111.6.0 up to 111.9.0: fixed in 111.9.0
—
Debian:10(1)
PackageVulnerable rangeFix by version rangeDependents
openssl1.1.1c-1, 1.1.1d-0+deb10u1, 1.1.1d-0+deb10u2
  • every version up to 1.1.1d-0+deb10u3: fixed in 1.1.1d-0+deb10u3
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • every version up to 1.1.1g-1: fixed in 1.1.1g-1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • every version up to 1.1.1g-1: fixed in 1.1.1g-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • every version up to 1.1.1g-1: fixed in 1.1.1g-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
openssl—
  • every version up to 1.1.1g-1: fixed in 1.1.1g-1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 6× in last 7d / 25× 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 136 total refreshes for this CVE.

  1. 2026-10-09 20:04 UTCEPSS rescore
  2. 2026-10-08 21:25 UTCEG score recompute
  3. 2026-10-08 16:38 UTCEPSS rescore
  4. 2026-10-07 23:44 UTCEPSS rescore
  5. 2026-10-06 15:13 UTCEPSS rescore
  6. 2026-10-03 14:22 UTCEPSS rescore
  7. 2026-10-02 16:22 UTCEPSS rescore
  8. 2026-09-30 15:14 UTCEG score recompute
  9. 2026-09-30 14:59 UTCEPSS rescore
  10. 2026-09-27 13:40 UTCEPSS rescore
  11. 2026-09-27 04:45 UTCOSV refresh
  12. 2026-09-26 15:54 UTCEPSS rescore
  13. 2026-09-24 14:00 UTCEPSS rescore
  14. 2026-09-24 14:00 UTCEPSS rescore
  15. 2026-09-22 14:43 UTCEPSS rescore
  16. 2026-09-21 20:28 UTCEPSS rescore
  17. 2026-09-18 19:23 UTCEPSS rescore
  18. 2026-09-17 19:22 UTCEPSS rescore
  19. 2026-09-17 19:22 UTCEPSS rescore
  20. 2026-09-16 14:04 UTCEPSS rescore
  21. 2026-09-15 03:06 UTCEPSS rescore
  22. 2026-09-15 03:06 UTCEPSS rescore
  23. 2026-09-12 14:56 UTCEPSS rescore
  24. 2026-09-11 14:48 UTCEPSS rescore
  25. 2026-09-10 09:29 UTCEPSS rescore
Show 75 more
  1. 2026-09-08 21:56 UTCEPSS rescore
  2. 2026-09-07 15:57 UTCEPSS rescore
  3. 2026-09-07 13:48 UTCOSV refresh
  4. 2026-09-06 13:44 UTCEPSS rescore
  5. 2026-09-05 15:24 UTCEPSS rescore
  6. 2026-09-04 13:57 UTCEPSS rescore
  7. 2026-09-04 05:03 UTCEPSS rescore
  8. 2026-09-02 14:08 UTCEPSS rescore
  9. 2026-08-30 19:14 UTCEPSS rescore
  10. 2026-08-30 01:18 UTCEPSS rescore
  11. 2026-08-26 14:42 UTCEPSS rescore
  12. 2026-08-25 13:45 UTCEPSS rescore
  13. 2026-08-21 23:45 UTCEPSS rescore
  14. 2026-08-20 23:15 UTCOSV refresh
  15. 2026-08-20 22:52 UTCEPSS rescore
  16. 2026-08-19 17:00 UTCEPSS rescore
  17. 2026-08-18 13:44 UTCEPSS rescore
  18. 2026-08-17 13:43 UTCEPSS rescore
  19. 2026-08-16 14:52 UTCEPSS rescore
  20. 2026-08-16 02:11 UTCEPSS rescore
  21. 2026-08-15 01:26 UTCEPSS rescore
  22. 2026-08-13 21:57 UTCEPSS rescore
  23. 2026-08-12 13:47 UTCEPSS rescore
  24. 2026-08-07 16:23 UTCEPSS rescore
  25. 2026-08-06 13:43 UTCEPSS rescore
  26. 2026-08-05 14:41 UTCOSV refresh
  27. 2026-08-04 15:06 UTCEPSS rescore
  28. 2026-08-01 04:12 UTCEPSS rescore
  29. 2026-07-30 16:25 UTCEPSS rescore
  30. 2026-07-30 01:27 UTCEPSS rescore
  31. 2026-07-28 15:32 UTCEPSS rescore
  32. 2026-07-26 14:51 UTCEPSS rescore
  33. 2026-07-25 14:15 UTCEPSS rescore
  34. 2026-07-25 14:14 UTCEPSS rescore
  35. 2026-07-24 14:14 UTCEPSS rescore
  36. 2026-07-23 14:15 UTCEPSS rescore
  37. 2026-07-23 14:15 UTCEPSS rescore
  38. 2026-07-23 01:50 UTCEG score recompute▲ 0.60
  39. 2026-07-22 22:36 UTCEG score recompute
  40. 2026-07-22 14:05 UTCEPSS rescore
  41. 2026-07-21 15:22 UTCEPSS rescore
  42. 2026-07-21 15:22 UTCEPSS rescore
  43. 2026-07-20 17:04 UTCEPSS rescore
  44. 2026-07-20 17:04 UTCEPSS rescore
  45. 2026-07-19 13:54 UTCOSV refresh
  46. 2026-07-19 02:26 UTCEPSS rescore
  47. 2026-07-19 02:26 UTCEPSS rescore
  48. 2026-07-16 16:59 UTCEPSS rescore
  49. 2026-07-15 16:55 UTCEPSS rescore
  50. 2026-07-15 01:57 UTCEPSS rescore
  51. 2026-07-13 22:27 UTCEPSS rescore
  52. 2026-07-13 22:27 UTCEPSS rescore
  53. 2026-07-13 06:10 UTCEPSS rescore
  54. 2026-07-13 06:10 UTCEPSS rescore
  55. 2026-07-12 05:44 UTCEPSS rescore
  56. 2026-07-11 08:25 UTCEPSS rescore
  57. 2026-07-11 08:25 UTCEPSS rescore
  58. 2026-07-09 19:07 UTCEPSS rescore
  59. 2026-07-08 15:12 UTCEPSS rescore
  60. 2026-07-05 02:27 UTCEPSS rescore
  61. 2026-07-02 00:01 UTCOSV refresh
  62. 2026-07-01 15:03 UTCEPSS rescore
  63. 2026-06-30 23:20 UTCEPSS rescore
  64. 2026-06-30 23:20 UTCEPSS rescore
  65. 2026-06-28 04:54 UTCEPSS rescore
  66. 2026-06-28 04:54 UTCEPSS rescore
  67. 2026-06-27 03:06 UTCEPSS rescore
  68. 2026-06-25 13:47 UTCEPSS rescore
  69. 2026-06-24 14:03 UTCEPSS rescore
  70. 2026-06-24 14:03 UTCEPSS rescore
  71. 2026-06-23 21:31 UTCEPSS rescore
  72. 2026-06-23 21:31 UTCEPSS rescore
  73. 2026-06-22 14:23 UTCEPSS rescore
  74. 2026-06-22 14:23 UTCEPSS rescore
  75. 2026-06-21 14:54 UTCEPSS rescore

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 GitHub PoC). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCirsl/CVE-2020-1967
    First seen Apr 28, 2020

    Proof of concept exploit about OpenSSL signature_algorithms_cert DoS flaw (CVE-2020-1967)

    Open source ↗

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2020-1967?
CVE-2020-1967 is a high vulnerability published on April 21, 2020. Server or client applications that call the SSLcheckchain() function during or after a TLS 1.3 handshake may crash due to a NULL pointer dereference as a result of incorrect handling of the "signaturealgorithmscert" TLS extension. The crash occurs if an invalid or unrecognised signature algorithm…
When was CVE-2020-1967 disclosed?
CVE-2020-1967 was first published on April 21, 2020, with the most recent update on October 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-1967 actively exploited?
CVE-2020-1967 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 53% probability of exploitation in the next 30 days (98th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2020-1967?
CVE-2020-1967 has a CVSS v3 base score of 7.5 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.1 (HIGH).
How do I remediate CVE-2020-1967?
A fix for CVE-2020-1967 is available: update to the fixed version the vendor names in its advisory.

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