follow-redirects: Incorrect Regular Expression
CVE-2026-111755 is a high-severity incorrect regular expression vulnerability in follow-redirects, with a CVSS 4.0 base score of 8.2 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected follow-redirects versions: >= 1.16.0, < 1.16.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.47% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of follow-redirects you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Follow-redirects | follow-redirects | >= 1.16.0, < 1.16.1 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Attack requirements
- PresentThe target must be in a specific state or configuration for the attack to work.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Confidentiality (vulnerable system)
- HighSerious loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- NoneNo loss of integrity on the vulnerable system.
- Availability (vulnerable system)
- NoneNo loss of availability on the vulnerable system.
- Confidentiality (other systems)
- NoneNo loss of confidentiality on systems beyond the vulnerable one.
- Integrity (other systems)
- NoneNo loss of integrity on systems beyond the vulnerable one.
- Availability (other systems)
- NoneNo loss of availability on systems beyond the vulnerable one.
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. Scored by CNA (github.com).
Official description
follow-redirects is a Node.js HTTP and HTTPS client wrapper that automatically follows redirects. From 1.16.0 until 1.16.1, escapeRegex leaves valid header-name metacharacters unescaped in sensitiveHeaders. When an application declares a sensitive header whose name contains ^ or | and follows a cross-origin or HTTPS-to-HTTP redirect, unescaped regular-expression metacharacters prevent the generated filter from matching the declared header name, and the credential header is forwarded to an attacker-controlled redirect target. This issue is fixed in version 1.16.1.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Incorrect Regular Expression
The product specifies a regular expression in a way that causes data to be improperly matched or compared.
How developers prevent this class of flaw
- Regular expressions can become error prone when defining a complex language even for those experienced in writing grammars. Determine if several smaller regular expressions simplify one large regular expression. Also, subject the regular expression to thorough testing techniques such as equivalence partitioning, boundary value analysis, and robustness. After testing and a reasonable confidence level is achieved, a regular expression may not be foolproof. If an exploit is allowed to slip through, then record the exploit and refactor the regular expression.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
References
Patches and release notes
Other vulnerabilities in follow-redirects
- 8.2 High severity
- 7.5 High severity
Recent Incorrect Regular Expression vulnerabilities
- 10.0 Critical severity
- 7.1 High severity
- 8.8 High severity
- 7.5 High severity
- 8.8 High severity
- 9.3 Critical severity
Spotted an error? Tell us.