CVE-2026-42175

The SSRF protection in requests-hardened prior to version 1.2.1 fails to block IP addresses within the RFC 6598 Shared Address Space (100.64.0.0/10). An attacker who can supply arbitrary URLs to requests-hardened could exploit this gap to access internal services hosted within 100.64.0.0/10. This is for example relevant in environments such as AWS EKS where 100.64.0.0/10 is commonly used as the default pod CIDR.

The impact is environment-dependent, deployments that utilize the affected CIDR range for internal networking are exposed to SSRF bypass, while others may not be affected.

The issue is resolved in version 1.2.1 by extending the IP filtering logic to explicitly block the RFC 6598 range in addition to standard private addresses, as well as blocking all other reserved addresses (such as multicast) to prevent the re-occurrence of similar issues.

Version 1.2.1 is now blocking the following CIDRs:

• 192.88.99.0/24 - 6to4 relay anycast
• 100.64.0.0/10 - CG-NAT
• 5f00::/16 - IPv6 Segment Routing
• 64:ff9b::/96 - used for IPv6 & IPv4 translation (NAT64)
• 2001:20::/28 - ORCHIDv2 (overlay identifiers)
• 224.0.0.0/4 - multicast
• ff00::/8 - multicast

Resources

• https://github.com/python/cpython/issues/119812
• https://github.com/saleor/requests-hardened/commit/b7403f88d3b3689e57435b75b51691a160aaeef5 - the fix itself
• https://github.com/saleor/requests-hardened/commit/a266b3958bb142bca515b3c230fdea19fbda327c - follow up, adding additional support for outdated Python versions (3.11.9 and 3.10.11 instead of only 3.11.15 and 3.10.20)
• https://github.com/saleor/requests-hardened/releases/tag/v1.2.1

Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.

CVE-2026-42175 has a CVSS score of 6.5 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.2.1); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-42175? CVE-2026-42175 is a medium-severity server-side request forgery (SSRF) vulnerability in requests-hardened (pip), affecting versions < 1.2.1. It is fixed in 1.2.1. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
2. How severe is CVE-2026-42175? CVE-2026-42175 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of requests-hardened are affected by CVE-2026-42175? requests-hardened (pip) versions < 1.2.1 is affected.
4. Is there a fix for CVE-2026-42175? Yes. CVE-2026-42175 is fixed in 1.2.1. Upgrade to this version or later.
5. Is CVE-2026-42175 exploitable, and should I be worried? Whether CVE-2026-42175 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-42175 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-42175? Upgrade requests-hardened to 1.2.1 or later.