CVE-2025-54887: JWE is missing AES-GCM authentication tag validation in encrypted JWE

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.3%, percentile 16: FIRST’s model estimates a 0.3% chance of exploitation activity in the next 30 days, higher than 16% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes jwe (RubyGems) <= 1.1.0, fixed in 1.1.1. Check your lockfile, including transitive dependencies.

What it is

jwe is a Ruby implementation of the RFC 7516 JSON Web Encryption (JWE) standard. In versions 1.1.0 and below, authentication tags of encrypted JWEs can be brute forced, which may result in loss of confidentiality for those JWEs and provide ways to craft arbitrary JWEs. This puts users at risk because JWEs can be modified to decrypt to an arbitrary value, decrypted by observing parsing differences and the GCM internal GHASH key can be recovered. Users are affected by this vulnerability even if they do not use an AES-GCM encryption algorithm for their JWEs. As the GHASH key may have been leaked, users must rotate the encryption keys after upgrading. This issue is fixed in version 1.1.1.

From the GitHub advisory

Overview The authentication tag of encrypted JWEs can be brute forced, which may result in loss of confidentiality for those JWEs and provide ways to craft arbitrary JWEs.

Impact - JWEs can be modified to decrypt to an arbitrary value - JWEs can be decrypted by observing parsing differences - The GCM internal GHASH key%20is%20the-,hash%20key,-%2C%20a%20string%20of) can be recovered

Am I Affected? You are affected by this vulnerability even if you do not use an AES-GCM encryption algorithm for your JWEs.

Patches The version 1.1.1 fixes the issue by adding the tag length check for the AES-GCM algorithm.

Important: As the GHASH key%20is%20the-,hash%20key,-%2C%20a%20string%20of) could have leaked, you must rotate the encryption keys after upgrading to version 1.1.1.

Weakness type: CWE-354.

Product: jwe (RubyGems) · Assigned by: GitHub_M · Published: 2025-08-08

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.25% probability of exploitation activity in the next 30 days; percentile 16.

Timeline

• 2025-08-07 — GitHub-reviewed advisory GHSA-c7p4-hx26-pr73 published (critical)
• 2025-08-08 — CVE record last updated
• 2025-08-08 — CVE record published by GitHub_M

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-c7p4-hx26-pr73 github.com
2. CVE.org record CVE-2025-54887 cve.org
3. NVD entry CVE-2025-54887 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com

Critical RubyGems advisories · Today’s Security Digest