CVE-2021-22947

MEDIUMNVD 5.95.9
EchelonGraph scoreMEDIUM confidence

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

Score 5.9 from GitHub Security Advisory published 2022-05-24. NVD baseline CVSS 5.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Elevated
5.9EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 3.0%CVSS: 5.9Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

When curl >= 7.20.0 and <= 7.78.0 connects to an IMAP or POP3 server to retrieve data using STARTTLS to upgrade to TLS security, the server can respond and send back multiple responses at once that curl caches. curl would then upgrade to TLS but not flush the in-queue of cached responses but instead continue using and trustingthe responses it got *before* the TLS handshake as if they were authenticated.Using this flaw, it allows a Man-In-The-Middle attacker to first inject the fake responses, then pass-through the TLS traffic from the legitimate server and trick curl into sending data back to the user thinking the attacker's injected data comes from the TLS-protected server.

CVSS v3
5.9
EG Score
5.9MEDIUMmedium confidence
EG Risk
43
EG Risk 43/100

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)
Severity59% × 45%
Impact severity (EG Severity): CVSS 5.9 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
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 public PoC (CISA Vulnrichment) · Automatable no (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.
EPSS PROB
3.0%
EPSS %ILE
87th
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 (5.9): severity, escalated by confirmed exploitation. This CVE's 5.9 is its impact severity (EG Severity), not escalated.

EG Severity
5.9 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
3.0% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-17). 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: 60 days if the affected system is publicly exposed; Fix on system upgrade 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; Track* at high (mission-essential systems).

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

Exploitation public PoC (CISA Vulnrichment) · Automatable no (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)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (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

September 29, 2021

Last Modified

October 14, 2026

Advisory Details (7)

Auto-updated Oct 14, 2026
Patch available.
Web page

Full Disclosure: APPLE-SA-2022-03-14-4 macOS Monterey 12.3

http://seclists.org/fulldisclosure/2022/Mar/29
Web page

[SECURITY] Fedora 35 Update: curl-7.79.1-1.fc35 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/APOAK4X73EJTAPTSVT7IRVDMUWVXNWGD/
Web page

[SECURITY] Fedora 33 Update: curl-7.71.1-11.fc33 - package-announce - Fedora mailing-lists

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RWLEC6YVEM2HWUBX67SDGPSY4CQB72OE/
Web pageMentions a patch (unverified)

[SECURITY] [DLA 2773-1] curl security update

https://lists.debian.org/debian-lts-announce/2021/09/msg00022.html

Vendor Advisories for CVE-2021-22947(2)

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

Patch Availability(5)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibcurl4-openssl-dev (7.35.0-1ubuntu2.20+esm8) @ trusty2026-10-14ubuntu
ubuntucurl (7.74.0-1ubuntu2.3) @ hirsute2026-10-14ubuntu
redhatrh-dotnet31-curl-0:7.61.1-22.el7_92022-04-13redhat
redhatcurl-0:7.61.1-12.el8_2.42022-02-22redhat
redhatcurl-0:7.61.1-18.el8_4.22021-11-02redhat

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

(20 across 20 ecosystems)
Alpine:v3.11(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 7.79.0-r0: fixed in 7.79.0-r0
—
Alpine:v3.12(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 7.79.0-r0: fixed in 7.79.0-r0
—
Alpine:v3.13(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 7.79.0-r0: fixed in 7.79.0-r0
—
Alpine:v3.14(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 7.79.0-r0: fixed in 7.79.0-r0
—
Alpine:v3.15(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 7.79.0-r0: fixed in 7.79.0-r0
—
Alpine:v3.16(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 7.79.0-r0: fixed in 7.79.0-r0
—
Alpine:v3.17(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 7.79.0-r0: fixed in 7.79.0-r0
—
Alpine:v3.18(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 7.79.0-r0: fixed in 7.79.0-r0
—
Alpine:v3.19(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 7.79.0-r0: fixed in 7.79.0-r0
—
Alpine:v3.20(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 7.79.0-r0: fixed in 7.79.0-r0
—
Alpine:v3.21(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 7.79.0-r0: fixed in 7.79.0-r0
—
Alpine:v3.22(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 7.79.0-r0: fixed in 7.79.0-r0
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 7.79.0-r0: fixed in 7.79.0-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 7.79.0-r0: fixed in 7.79.0-r0
—
Debian:10(1)
PackageVulnerable rangeFix by version rangeDependents
curl7.64.0-4, 7.64.0-4+deb10u1, 7.64.0-4+deb10u2
  • every version up to 7.64.0-4+deb10u3: fixed in 7.64.0-4+deb10u3
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
curl7.74.0-1.3, 7.74.0-1.3+deb11u1
  • every version up to 7.74.0-1.3+deb11u2: fixed in 7.74.0-1.3+deb11u2
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 7.79.1-1: fixed in 7.79.1-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 7.79.1-1: fixed in 7.79.1-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • every version up to 7.79.1-1: fixed in 7.79.1-1
—
Debian:9(1)
PackageVulnerable rangeFix by version rangeDependents
curl7.52.1-5 ... 7.52.1-5+deb9u9 (16 versions)
  • every version up to 7.52.1-5+deb9u16: fixed in 7.52.1-5+deb9u16
—

Weakness Classification(2)

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

Additional Vendor Advisories

(5)

Data Freshness Timeline

(refreshed 8× in last 7d / 39× 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 94 of 239 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. 6 repeat rows among the latest 100 are merged into the row they repeat. The 145 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-23 16:28 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  2. 2026-10-22 16:29 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  3. 2026-10-21 16:28 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  4. 2026-10-20 16:28 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  5. 2026-10-19 16:28 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  6. 2026-10-18 16:28 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  7. 2026-10-18 09:09 UTCEG score recompute
  8. 2026-10-17 16:28 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  9. 2026-10-16 16:33 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  10. 2026-10-15 16:28 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  11. 2026-10-14 16:28 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  12. 2026-10-14 12:26 UTCVendor advisory
  13. 2026-10-14 12:26 UTCGHSA enrichmentGHSA-94jh-wwgf-cmmc · GitHub CVSS 5.9
  14. 2026-10-14 11:40 UTCEG score recompute
  15. 2026-10-14 11:40 UTCVendor advisory
  16. 2026-10-14 11:40 UTCGHSA enrichmentGHSA-94jh-wwgf-cmmc · GitHub CVSS 5.9
  17. 2026-10-13 16:28 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  18. 2026-10-12 19:23 UTCEG score recompute
  19. 2026-10-12 16:29 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  20. 2026-10-11 23:49 UTCEG score recompute
  21. 2026-10-11 13:43 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  22. 2026-10-10 19:56 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  23. 2026-10-09 20:04 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  24. 2026-10-08 16:39 UTCEPSS rescoreEPSS 3.0% · 87th percentile
  25. 2026-10-07 23:44 UTCEPSS rescoreEPSS 3.0% · 86th percentile
Show 69 more
  1. 2026-10-07 19:35 UTCOSV refresh
  2. 2026-10-06 15:13 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  3. 2026-10-05 17:40 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  4. 2026-10-04 23:18 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  5. 2026-10-03 14:22 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  6. 2026-10-02 16:22 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  7. 2026-10-01 19:46 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  8. 2026-09-30 15:30 UTCEG score recompute
  9. 2026-09-30 15:00 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  10. 2026-09-28 13:47 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  11. 2026-09-27 13:41 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  12. 2026-09-26 15:54 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  13. 2026-09-26 00:21 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  14. 2026-09-24 14:00 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  15. 2026-09-23 13:44 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  16. 2026-09-22 14:44 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  17. 2026-09-21 20:28 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  18. 2026-09-19 15:37 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  19. 2026-09-18 19:23 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  20. 2026-09-18 01:36 UTCOSV refresh
  21. 2026-09-17 19:23 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  22. 2026-09-16 14:04 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  23. 2026-09-15 03:06 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  24. 2026-09-13 16:43 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  25. 2026-09-12 14:57 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  26. 2026-09-11 09:33 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  27. 2026-09-10 09:29 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  28. 2026-09-08 21:56 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  29. 2026-09-07 15:58 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  30. 2026-09-06 13:44 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  31. 2026-09-05 15:25 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  32. 2026-09-04 13:57 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  33. 2026-09-04 05:03 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  34. 2026-09-02 14:08 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  35. 2026-09-01 13:50 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  36. 2026-09-01 03:32 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  37. 2026-08-30 19:14 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  38. 2026-08-30 02:43 UTCOSV refresh
  39. 2026-08-30 01:19 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  40. 2026-08-28 21:37 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  41. 2026-08-27 14:22 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  42. 2026-08-26 14:42 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  43. 2026-08-25 13:45 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  44. 2026-08-23 00:16 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  45. 2026-08-21 23:46 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  46. 2026-08-20 22:52 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  47. 2026-08-19 17:01 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  48. 2026-08-18 13:45 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  49. 2026-08-17 13:43 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  50. 2026-08-16 14:52 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  51. 2026-08-16 02:11 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  52. 2026-08-15 01:27 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  53. 2026-08-13 21:57 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  54. 2026-08-13 13:21 UTCOSV refresh
  55. 2026-08-12 13:47 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  56. 2026-08-11 13:38 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  57. 2026-08-09 13:43 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  58. 2026-08-08 16:33 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  59. 2026-08-07 16:23 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  60. 2026-08-06 13:43 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  61. 2026-08-05 19:14 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  62. 2026-08-04 15:06 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  63. 2026-08-04 10:34 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  64. 2026-08-03 10:32 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  65. 2026-08-02 02:24 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  66. 2026-08-01 04:12 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  67. 2026-07-30 16:25 UTCEPSS rescoreEPSS 3.0% · 86th percentile
  68. 2026-07-30 01:27 UTCEPSS rescoreEPSS 2.9% · 85th percentile
  69. 2026-07-28 20:21 UTCOSV refresh

Frequently asked(5)

What is CVE-2021-22947?
CVE-2021-22947 is a medium-severity vulnerability; its CVE record was published on September 29, 2021. When curl >= 7.20.0 and <= 7.78.0 connects to an IMAP or POP3 server to retrieve data using STARTTLS to upgrade to TLS security, the server can respond and send back multiple responses at once that curl caches. curl would then upgrade to TLS but not flush the in-queue of cached responses but…
When was the CVE record for CVE-2021-22947 published?
The CVE record for CVE-2021-22947 was published on September 29, 2021. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 14, 2026; the record at its source may have been updated since.
Is CVE-2021-22947 actively exploited?
CVE-2021-22947 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 3.0% probability of exploitation in the next 30 days (87th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-22947?
CVE-2021-22947 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2021-22947?
A fix for CVE-2021-22947 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2021-22947 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-2021-22947

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