Security readout for executives and security teams
Plain-English summary
This curl/libcurl issue can let a malicious HTTPS proxy silently interfere with a connection under specific TLS 1.3 conditions. The business risk is highest where systems route outbound traffic through HTTPS proxies and rely on curl for trusted downloads, API calls, or automation.
Executive priority
Treat this as a targeted remediation item, not an internet-wide emergency. Prioritize environments that use HTTPS proxies or embedded libcurl in operational systems, especially where curl handles trusted downloads or API traffic.
Technical view
curl 7.63.0 through 7.75.0 can mishandle TLS 1.3 session tickets when an HTTPS proxy is used. libcurl may confuse proxy tickets with origin-server tickets, resume the wrong session, and skip the expected host certificate validation path, enabling unnoticed MITM under constrained conditions.
Likely exposure
Exposure is limited to curl or libcurl 7.63.0 through 7.75.0 using HTTPS proxies with TLS 1.3. Appliances, servers, scripts, and products embedding libcurl may be affected if their vendor shipped those versions.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation evidence. Attack viability requires a malicious HTTPS proxy position and a certificate curl accepts for the targeted server, unless certificate verification was disabled.
Researcher notes
The core weakness is TLS channel confusion: proxy session tickets can be treated as origin tickets, leading to incorrect session resumption and certificate-check bypass behavior. Evidence supports affected versions and conditions, but the bundle does not provide active exploitation claims.
Mitigation direction
- Inventory curl and libcurl versions across hosts, containers, and embedded products.
- Upgrade affected curl/libcurl packages using vendor security advisories.
- Review vendor guidance for products embedding libcurl, including appliances and bundled runtimes.
- Avoid disabling TLS certificate verification in curl-based tooling.
- Reduce reliance on untrusted HTTPS proxies for sensitive outbound connections.
Validation and detection
- Confirm deployed curl/libcurl versions are not in the affected 7.63.0 through 7.75.0 range.
- Identify workloads using HTTPS proxy configuration with curl or libcurl.
- Check operating system and product advisories for fixed package availability.
- Review automation and applications for disabled certificate verification settings.
- Prioritize validation on systems handling trusted downloads, credentials, or API calls.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-300: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-22890 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 4.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N2.81.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://hackerone.com/reports/1129529CVE reference · x_refsource_MISC
- https://curl.se/docs/CVE-2021-22890.htmlCVE reference · x_refsource_MISC
- FEDORA-2021-cab5c9befbCVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-065371f385CVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-26a293c72bCVE reference · vendor-advisory, x_refsource_FEDORA
- GLSA-202105-36CVE reference · vendor-advisory, x_refsource_GENTOO
- https://www.oracle.com//security-alerts/cpujul2021.htmlCVE reference · x_refsource_MISC
- https://security.netapp.com/advisory/ntap-20210521-0007/CVE reference · x_refsource_CONFIRM
- https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdfCVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Channel Accessible by Non-Endpoint
Channel Accessible by Non-Endpoint represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.