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).
CVE-2020-1967
“▲” beside the score: it is higher than NVD's CVSS score.
Score elevated to 8.1 because EPSS predicted 53% probability of exploitation within the next 30 days (98th percentile of EPSS-scored CVEs) when EchelonGraph scored this CVE. NVD baseline CVSS 7.5 retained for reference. Confidence: see factors.
Also known asEUVD-2021-1780 (ENISA EUVD) · GHSA-jq65-29v4-4x35 (GitHub Security Advisories) · RUSTSEC-2020-0015 (OSV.dev)Source: ENISA EUVD
- High exploitation likelihood — EPSS 53%
- Public exploit or proof-of-concept code is available
A fix is available — apply it.
- CVSS v3
- 7.5
- EG Score
- 8.1HIGHhigh confidence
- EG Risk
- 70EG Risk 70/100
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.Exploitation53% × 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
- 53%
- EPSS %ILE
- 98th
- 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 (8.1): severity, escalated by confirmed exploitation. This CVE's 8.1 is EPSS's lift toward 9.0 from its impact severity (EG Severity, CVSS 7.5 HIGH): a likelihood of exploitation, not impact.
- EG Severity
- 7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 53% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). 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
April 21, 2020
Last Modified
October 8, 2026
Advisory Details (6)
Auto-updated Oct 8, 2026Pony Mail
https://lists.apache.org/thread.html/r94d6ac3f010a38fccf4f432b12180a13fa1cf303559bd805648c9064%40%3Cdev.tomcat.apache.org%3EPony Mail
https://lists.apache.org/thread.html/r66ea9c436da150683432db5fbc8beb8ae01886c6459ac30c2cea7345%40%3Cdev.tomcat.apache.org%3EGitHub - irsl/CVE-2020-1967: Proof of concept exploit about OpenSSL signature_algorithms_cert DoS flaw (CVE-2020-1967) · GitHub
https://github.com/irsl/CVE-2020-1967oss-security - [CVE-2020-1967] OpenSSL 1.1.1d+ Segmentation fault in SSL_check_chain
http://www.openwall.com/lists/oss-security/2020/04/22/2Full Disclosure: CVE-2020-1967: proving sigalg != NULL
http://seclists.org/fulldisclosure/2020/May/5Patch Availability(1)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| rust | openssl-src @ 111.9.0 (fixes >= 111.6.0, < 111.9.0) | — | ghsa |
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
(24 across 22 ecosystems)
Alpine:v3.15(2)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
| openssl3 | — |
| — |
Alpine:v3.16(2)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
| openssl3 | — |
| — |
Alpine:v3.10(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Alpine:v3.11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Alpine:v3.12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Alpine:v3.13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Alpine:v3.14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Alpine:v3.17(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Alpine:v3.18(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Alpine:v3.19(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Alpine:v3.20(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Alpine:v3.21(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Alpine:v3.22(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Alpine:v3.23(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Alpine:v3.24(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Alpine:v3.9(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
crates.io(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl-src | — |
| — |
Debian:10(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | 1.1.1c-1, 1.1.1d-0+deb10u1, 1.1.1d-0+deb10u2 |
| — |
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| openssl | — |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 34× 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 92 of 156 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. 8 repeat rows among the latest 100 are merged into the row they repeat. The 64 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-01 08:37 UTCGHSA enrichmentGHSA-jq65-29v4-4x35 · GitHub severity HIGH · GitHub CVSS 7.5
- 2026-11-01 08:37 UTCEG score recompute
- 2026-10-31 16:28 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-30 16:29 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-29 16:28 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-29 07:45 UTCEG score recompute
- 2026-10-29 06:55 UTCOSV refresh
- 2026-10-28 16:27 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-27 16:27 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-25 18:48 UTCEG score recompute
- 2026-10-25 16:28 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-24 16:28 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-23 16:27 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-22 16:29 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-21 16:28 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-21 12:47 UTCEG score recompute
- 2026-10-20 16:28 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-19 16:27 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-18 09:30 UTCEG score recompute
- 2026-10-17 16:28 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-16 16:33 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-15 16:27 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-14 16:28 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-13 16:28 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-12 19:42 UTCEG score recompute
Show 67 moreShow fewer
- 2026-10-12 00:06 UTCEG score recompute
- 2026-10-11 13:43 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-10 19:56 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-09 20:04 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-08 21:25 UTCEG score recompute
- 2026-10-08 16:38 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-07 23:44 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-06 15:13 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-03 14:22 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-10-02 16:22 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-30 15:14 UTCEG score recompute
- 2026-09-30 14:59 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-27 13:40 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-27 04:45 UTCOSV refresh
- 2026-09-26 15:54 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-24 14:00 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-22 14:43 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-21 20:28 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-18 19:23 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-17 19:22 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-16 14:04 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-15 03:06 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-12 14:56 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-11 14:48 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-10 09:29 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-08 21:56 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-07 15:57 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-07 13:48 UTCOSV refresh
- 2026-09-06 13:44 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-05 15:24 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-04 13:57 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-04 05:03 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-09-02 14:08 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-30 19:14 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-30 01:18 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-26 14:42 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-25 13:45 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-21 23:45 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-20 23:15 UTCOSV refresh
- 2026-08-20 22:52 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-19 17:00 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-18 13:44 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-17 13:43 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-16 14:52 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-16 02:11 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-15 01:26 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-13 21:57 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-12 13:47 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-07 16:23 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-06 13:43 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-05 14:41 UTCOSV refresh
- 2026-08-04 15:06 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-08-01 04:12 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-07-30 16:25 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-07-30 01:27 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-07-28 15:32 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-07-26 14:51 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-07-25 14:14 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-07-24 14:14 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-07-23 14:15 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-07-23 01:50 UTCEG score recompute▲ 0.60
- 2026-07-22 22:36 UTCEG score recompute
- 2026-07-22 14:05 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-07-21 15:22 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-07-20 17:04 UTCEPSS rescoreEPSS 53% · 98th percentile
- 2026-07-19 13:54 UTCOSV refresh
- 2026-07-19 02:26 UTCEPSS rescoreEPSS 53% · 98th percentile
Publicly available exploits
(1 reference)Public exploit code is referenced for this CVE (1 GitHub PoC). Defenders should treat patch urgency accordingly.
- GitHub PoCirsl/CVE-2020-1967Published 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)
Same product
10 shownAlpine:v3.10:openssl
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- CVE-2019-1551EG 5.3EPSS p97MEDIUM
- CVE-2019-1547EG 4.7MEDIUM
- CVE-2019-1563EG 3.7EPSS p90LOW
- CVE-2021-3450EG 7.4EPSS p97HIGH
- CVE-2019-1543EG 7.4EPSS p93HIGH
- CVE-2018-0734EG 5.9EPSS p96MEDIUM
Frequently asked(5)
What is CVE-2020-1967?
When was CVE-2020-1967 made public?
Is CVE-2020-1967 actively exploited?
What is the CVSS score of CVE-2020-1967?
How do I remediate CVE-2020-1967?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2020-1967
Is Your Infrastructure Affected by CVE-2020-1967?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.