CVE-2021-22947

mediumpriority · track · 25OT risk · elevatedEPSS 0.030 · 87 %ileDEEUFRRUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
3.01% (87th) EPSS
CVSS 4.3 · medium
Is it mine?
99 products
Check your exposure
Who says so?
9 sources
cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-26

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.

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

02

cvss

Technical severity, 0–10. One row per scoring source.

8.2
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4.3–8.2

v2.04.3mediumAV:N/AC:M/Au:N/C:N/I:P/A:Nprimary · NVD / NIST USexploitability 8.6 · impact 2.9
v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:Nprimary · NVD / NIST USexploitability 2.2 · impact 3.6
v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N/E:P/RL:O/RC:Csecondary · CISA US
v3.18.2highAV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:Nsecondary · FSTEC (BDU) RU
v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:Nsecondary · ENISA EU
v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:Nsecondaryexploitability 2.2 · impact 3.6
v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N/E:P/RL:O/RC:Csecondary · Siemens ProductCERT DE
v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:Nsecondary · Phoenix Contact PSIRT DE
v3.15.4mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N/E:Usecondary · CVSS-BT (t0sche)
03

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: poc · Automatable: no · Technical Impact: partialcoordinatorcisa_ssvcUS
04

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-345USprimaryCWE-310USCWE-310USCWE-345USCWE-345USCWE-345USCWE-345US
05

affected products (99)

Products and version ranges known to be affected.

showing 20 of 99
06

advisories (13)

Vendor and ecosystem advisories describing this.

  • SSA-389290SSA-389290: Third-Party Component Vulnerabilities in SINEC INS2022-03-08csaf · siemens_psirtDE

    71 vulnerabilities in third-party components as Node.js, cURL, SQLite, CivetWeb and DNS(ISC BIND) could allow an attacker to interfere with the affected product in various ways. Siemens has released an update for SINEC INS and recommends to update to the latest versions.

  • SSA-398330SSA-398330: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP >= V3.1.0 and < V3.1.52023-12-12csaf · siemens_psirtDE

    Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version >= V3.1.0 and < V3.1.5 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). These GNU/Linux vulnerabilities have been externally identified. Siemens has released new versions for the affected products and recommends to update to the latest versions. SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP >= V3.1.0 and < V3.1.5 are no longer maintained and there won't be any update to the CVE list anymore. Please update to the latest version. Note: This SSA advises vulnerabilities for firmware version V3.1 only; for versions < V3.1 refer to Siemens Security Bulletin SSB-439005 (https://cert-portal.siemens.com/productcert/html/ssb-439005.html).

  • VDE-2022-010PHOENIX CONTACT: Multiple Linux component vulnerabilities fixed in latest AXC F x152 LTS release2022-04-12csaf · phoenix_contact_psirtDE

    PLCnext Control AXC F x152 is certified according to IEC 62443-4-1 and IEC 62443-4-2. This certification requires that all third-party components used in the firmware are regularly checked for known vulnerabilities. Firmware components in version 2021.06 had already been updated. For the 2022.0 LTS version more firmware components have been updated implicitly fixing the vulnerabilities listed. The vulnerabilities listed above have not been individually verified in terms of actual impact and/or limitations in combination with the affected products listed. The current LTS release 2022.0 LTS contains updates of integrated third-party libraries, SDKs and other third-party software to address these issues nevertheless. UPDATE A (April 4th, 2022): Added RFC 4072 (Art. No. 1051328) and fixed affected version of AXC F 3152

  • WID-SEC-W-2022-0875cURL: Mehrere SchwachstellenDeutsch2021-09-14csaf · cert_bundDE

    Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in cURL ausnutzen, um einen Denial of Service Angriff durchzuführen oder die Kryptographie zu umgehen.

  • WID-SEC-W-2022-1056Apple macOS: Mehrere SchwachstellenDeutsch2022-03-14csaf · cert_bundDE

    Ein entfernter anonymer, authentisierter, lokaler oder physischer Angreifer kann mehrere Schwachstellen in Apple macOS ausnutzen, , um seine Privilegien zu erweitern, vertrauliche Informationen offenzulegen, Sicherheitsmaßnahmen zu umgehen, einen Denial-of-Service-Zustand herbeizuführen, einen Spoofing-Angriff durchzuführen und beliebigen Code auszuführen.

  • WID-SEC-W-2022-1461IBM Spectrum Protect: Mehrere SchwachstellenDeutsch2022-09-18csaf · cert_bundDE

    Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in IBM Spectrum Protect ausnutzen, um seine Privilegien zu erweitern, beliebigen Programmcode mit Administratorrechten auszuführen, Informationen offenzulegen, Dateien zu manipulieren, einen Cross-Site-Scripting-Angriff durchzuführen, einen Denial of Service Zustand herbeizuführen oder Sicherheitsvorkehrungen zu umgehen.

  • WID-SEC-W-2023-1350Splunk Splunk Enterprise: Mehrere Schwachstellen in Komponenten von DrittanbieternDeutsch2023-06-01csaf · cert_bundDE

    Ein Angreifer kann mehrere Schwachstellen in Splunk Splunk Enterprise in diversen Komponenten von Drittanbietern ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen.

  • WID-SEC-W-2023-2229Splunk Splunk Enterprise: Mehrere SchwachstellenDeutsch2023-08-30csaf · cert_bundDE

    Ein entfernter, authentifizierter Angreifer kann mehrere Schwachstellen in Splunk Splunk Enterprise ausnutzen, um beliebigen Code auszuführen, einen 'Denial of Service'-Zustand zu verursachen, seine Privilegien zu erweitern und weitere, nicht spezifizierte Auswirkungen zu verursachen.

  • WID-SEC-W-2026-0180Dell Data Protection Advisor: Mehrere SchwachstellenDeutsch2026-01-20csaf · cert_bundDE

    Ein Angreifer kann mehrere Schwachstellen in Dell Data Protection Advisor ausnutzen, um beliebigen Code auszuführen, einen Denial-of-Service-Zustand zu erzeugen, Sicherheitsmaßnahmen zu umgehen und nicht näher spezifizierte Angriffe zu starten.

  • ICSA-22-069-09Siemens SINEC INS2022-03-08icsa · cisa_csaf_otUS

    71 vulnerabilities in third-party components as Node.js, cURL, SQLite, CivetWeb and DNS(ISC BIND) could allow an attacker to interfere with the affected product in various ways. Siemens has released an update for SINEC INS and recommends to update to the latest versions.

  • ICSA-23-348-10Siemens SIMATIC S7-15002023-12-12icsa · cisa_csaf_otUS

    Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version >= V3.1.0 and < V3.1.5 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). These GNU/Linux vulnerabilities have been externally identified. Siemens has released new versions for the affected products and recommends to update to the latest versions. Note: This SSA advises vulnerabilities for firmware version V3.1 only; for versions < V3.1 refer to Siemens Security Bulletin SSB-439005 ( https://cert-portal.siemens.com/productcert/html/ssb-439005.html).

  • CERTFR-2026-AVI-1385Multiples vulnérabilités dans les produits VMwareFrançais2026-10-26vendor · certfrFR
  • CURL-CVE-2021-22947STARTTLS protocol injection via MITM2021-09-15vendor · osvUS

    When curl connects to an IMAP, POP3, SMTP or FTP server to exchange data securely using STARTTLS to upgrade the connection to TLS level, the server can still respond and send back multiple responses before the TLS upgrade. Such multiple *pipelined* responses are cached by curl. curl would then upgrade to TLS but not flush the in-queue of cached responses and instead use and trust the 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. Over POP3 and IMAP an attacker can inject fake response data.

07

also known as (4)

Other names and identifiers for this entity.

08

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bducert_bundcisa_csaf_otsiemens_psirtphoenix_contact_psirtcertfrosvNVDCVE.orgMITRE
published 2021-09-29modified 2026-06-17
10

references (97)

External citations — patches, advisories, analysis.

scry

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