CVE-2019-11841

A message-forgery issue was discovered in crypto/openpgp/clearsign/clearsign.go in supplementary Go cryptography libraries 2019-03-25. According to the OpenPGP Message Format specification in RFC 4880 chapter 7, a cleartext signed message can contain one or more optional "Hash" Armor Headers. The "Hash" Armor Header specifies the message digest algorithm(s) used for the signature. However, the Go clearsign package ignores the value of this header, which allows an attacker to spoof it. Consequently, an attacker can lead a victim to believe the signature was generated using a different message digest algorithm than what was actually used. Moreover, since the library skips Armor Header parsing in general, an attacker can not only embed arbitrary Armor Headers, but also prepend arbitrary text to cleartext messages without invalidating the signatures.

CVE-2019-11841 has a CVSS score of 5.9 (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 (0.0.0-20190424203555-c05e17bb3b2d); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2019-11841? CVE-2019-11841 is a medium-severity security vulnerability in golang.org/x/crypto (go), affecting versions < 0.0.0-20190424203555-c05e17bb3b2d. It is fixed in 0.0.0-20190424203555-c05e17bb3b2d.
2. How severe is CVE-2019-11841? CVE-2019-11841 has a CVSS score of 5.9 (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 golang.org/x/crypto are affected by CVE-2019-11841? golang.org/x/crypto (go) versions < 0.0.0-20190424203555-c05e17bb3b2d is affected.
4. Is there a fix for CVE-2019-11841? Yes. CVE-2019-11841 is fixed in 0.0.0-20190424203555-c05e17bb3b2d. Upgrade to this version or later.
5. Is CVE-2019-11841 exploitable, and should I be worried? Whether CVE-2019-11841 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-2019-11841 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-2019-11841? Upgrade golang.org/x/crypto to 0.0.0-20190424203555-c05e17bb3b2d or later.