CVE-2021-22890

mediumpriority · track · 16EPSS 0.031 · 88 %ileDEEURUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
3.06% (88th) EPSS
CVSS 4.3 · medium
Is it mine?
60 products
Check your exposure
Who says so?
7 sources
cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

curl 7.63.0 to and including 7.75.0 includes vulnerability that allows a malicious HTTPS proxy to MITM a connection due to bad handling of TLS 1.3 session tickets. When using a HTTPS proxy and TLS 1.3, libcurl can confuse session tickets arriving from the HTTPS proxy but work as if they arrived from the remote server and then wrongly "short-cut" the host handshake. When confusing the tickets, a HTTPS proxy can trick libcurl to use the wrong session ticket resume for the host and thereby circumvent the server TLS certificate check and make a MITM attack to be possible to perform unnoticed. Note that such a malicious HTTPS proxy needs to provide a certificate that curl will accept for the MITMed server for an attack to work - unless curl has been told to ignore the server certificate check.

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.

4.3
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 3.4–4.3

v2.04.3mediumAV:N/AC:M/Au:N/C:N/I:P/A:Nprimary · NVD / NIST USexploitability 8.6 · impact 2.9
v3.13.7lowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:Nprimary · NVD / NIST USexploitability 2.2 · impact 1.4
v3.13.7lowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:Csecondary · CISA US
v3.13.7lowAV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:Nsecondary · FSTEC (BDU) RU
v3.14.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:Nsecondary · ENISA EU
v3.14.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:Nsecondaryexploitability 2.8 · impact 1.4
v3.13.7lowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:Csecondary · Siemens ProductCERT DE
v3.13.4lowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/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.

05

affected products (60)

Products and version ranges known to be affected.

06

advisories (8)

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).

  • 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-2023-1634cURL: Mehrere SchwachstellenDeutsch2021-03-30csaf · cert_bundDE

    Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in cURL ausnutzen, um Informationen offenzulegen und um Sicherheitsvorkehrungen zu umgehen.

  • 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.

  • 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).

  • CURL-CVE-2021-22890TLS 1.3 session ticket proxy host mix-up2021-03-31vendor · osvUS

    Enabled by default, libcurl supports the use of TLS 1.3 session tickets to resume previous TLS sessions to speed up subsequent TLS handshakes. When using an HTTPS proxy and TLS 1.3, libcurl can confuse session tickets arriving from the HTTPS proxy but work as if they arrived from the remote server and then wrongly "short-cut" the host handshake. The reason for this confusion is the modified sequence from TLS 1.2 when the session ids would provided only during the TLS handshake, while in TLS 1.3 it happens post hand-shake and the code was not updated to take that changed behavior into account. When confusing the tickets, an HTTPS proxy can trick libcurl to use the wrong session ticket resume for the host and thereby circumvent the server TLS certificate check and make a MITM attack to be possible to perform unnoticed. This flaw can allow a malicious HTTPS proxy to MITM the traffic. Such a malicious HTTPS proxy needs to provide a certificate that curl accepts for the MITMed server for an attack to work - unless curl has been told to ignore the server certificate check.

07

also known as (4)

Other names and identifiers for this entity.

08

sources

Which sources assert this record, and when.

10

references (45)

External citations — patches, advisories, analysis.

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