Golang/x/crypto message forgery vulnerability

中 5.9CVE-2019-11841 · GHSA-x3jr-pf6g-c48f · GO-2023-1992 · 22/05/2019 公開 · 17/06/2026 更新

要点

CVE-2019-11841 は golang.org/x/crypto, crypto (golang) に影響する深刻度「中」 (CVSS 5.9) の脆弱性です。
今後30日間に悪用される確率（EPSS）：2.0%（全脆弱性の 80.8% より高い）。
対処：0.0.0-20190424203555-c05e17bb3b2d 以降に更新してください。

パッケージ	影響を受けるバージョン	修正済みバージョン
golang.org/x/crypto Go	`< 0.0.0-20190424203555-c05e17bb3b2d`	`0.0.0-20190424203555-c05e17bb3b2d`
crypto golang	`= 2019-03-25`	修正版なし

概要

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.

NVD の説明

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.