CVE-2026-65625: jose · Pure-Erlang AES-GCM Fallback
Affects joseSource GCVE Database
Not known to be exploited · CVSS 5.9 Medium.
Data as of 28 Oct 2026, 22:28 UTC
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 26 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10josepkg:deb/ubuntu/jose?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 20.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=focalOther threats | Affected
| Fixed in– |
Ubuntu 18.04 LTSjosepkg:deb/ubuntu/jose?arch=source&distro=bionicOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
The pure-Erlang AES-GCM fallback in jose_jwa_aes derives the number of verified authentication tag bits from the attacker-supplied tag itself. In the {aes_gcm, Bits} clause of block_decrypt/4, the incoming tag is guarded only by is_binary/1, with no check on its length. Verification in gcm_block_decrypt/6 then computes TBits = bit_size(T) and compares only those bits of the real 128-bit tag. An attacker who controls a JWE token can truncate the authentication tag to as little as 8 bits, so only 8 bits are ever checked. This reduces forgery resistance from 2^-128 to 2^-8, and a forged ciphertext is reliably accepted as authentic within 256 attempts without knowledge of the key (an authentication tag forgery and integrity bypass). Supplying a tag longer than 128 bits instead causes a badmatch that crashes the decrypting process. The fallback is reached through the public JWE decryption path whenever AES-GCM is not provided by a native crypto NIF, for example on FIPS or stripped or older OTP builds. This issue affects jose: from 1.2.0 before 1.11.13.
References
- ubuntu.com/security/CVE-2026-65625 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-65625 (opens in a new tab)
- cna.erlef.org/cves/cve-2026-65625.html (opens in a new tab)
- github.com (opens in a new tab)
- github.com/potatosalad/erlang-jose (opens in a new tab)
- github.com/potatosalad/erlang-jose/commit/3fa1f8e3efda0da5ce6f4c9984789f979dc02740 (opens in a new tab)
- github.com/potatosalad/erlang-jose/commit/8848b172575fb7d7e1e2977e8ae0a21678d2157a (opens in a new tab)
- github.com/potatosalad/erlang-jose/security/advisories/ghsa-6gxw-6f7r-cjr6 (opens in a new tab)
- hex.pm/packages/jose (opens in a new tab)
- repo.hex.pm (opens in a new tab)
- github.com/cveproject/cvelistv5/tree/main/cves/2026/65xxx/cve-2026-65625.json (opens in a new tab)
- nvd.nist.gov/vuln/detail/cve-2026-65625 (opens in a new tab)
- osv.dev/vulnerability/eef-cve-2026-65625 (opens in a new tab)