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CVE-2026-65625— Attacker-controlled AES-GCM authentication tag length allows tag forgery in jose

Quick assessment

Affected
potatosalad jose
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

jose_jwa_aes 模块中纯 Erlang 实现的 AES-GCM 降级方案存在漏洞：该方案从攻击者提供的标签（tag）本身推导需要验证的认证标签比特数。在 block_decrypt/4 函数的 {aes_gcm, Bits} 子句中，传入的标签仅通过 is_binary/1 进行类型检查，未对其长度进行任何验证。随后在 gcm_block_decrypt/6 中执行验证时，系统计算 TBits = bit_size(T)，并仅比对真实 128 位标签中的前 TBits 个比特。 若攻击者能够控制 JWE

CVSS 5.9 · Medium
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I. Basic Information for CVE-2026-65625

Vulnerability Information
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Vulnerability Title
Attacker-controlled AES-GCM authentication tag length allows tag forgery in jose
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
完整性检查值验证不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
potatosalad jose 1.2.0 ~ 1.11.13 cpe:2.3:a:potatosalad:jose:*:*:*:*:*:*:*:*
potatosalad jose 8848b172575fb7d7e1e2977e8ae0a21678d2157a ~ 3fa1f8e3efda0da5ce6f4c9984789f979dc02740 cpe:2.3:a:potatosalad:jose:*:*:*:*:*:*:*:*

II. Public POCs for CVE-2026-65625

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III. Intelligence Information for CVE-2026-65625

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Patches & Fixes for CVE-2026-65625 (1)

Vendor Advisories for CVE-2026-65625 (1)

Other References for CVE-2026-65625 (1)

Same Patch Batch · potatosalad · 2026-10-26 · 8 CVEs total

CVE-2026-65629 7.4 HIGH Weak PBKDF2 parameters for password-encrypted private-key export in jose
CVE-2026-65627 6.9 MEDIUM Decompression bomb via unbounded zlib:inflate in jose_jwe_zip:uncompress/2
CVE-2026-65631 6.9 MEDIUM erlang-jose RSA JWK parsing attempts to factor an attacker-controlled modulus, enabling CP
CVE-2026-65626 5.9 MEDIUM Bleichenbacher padding oracle in RSAES-PKCS1-v1_5 decryption in jose
CVE-2026-65628 5.9 MEDIUM Infinite recursion (CPU denial-of-service) in JOSE.JWK.shared_secret/2 on mismatched key t
CVE-2026-65630 5.9 MEDIUM Timing side-channel in pure-Erlang X25519 scalar multiplication leaks the private key in j
CVE-2026-65632 5.1 MEDIUM ECDSA signature length is not validated in jose, allowing signature malleability

IV. Related Vulnerabilities

Same product: jose
Same vendor: potatosalad
Same weakness: CWE-354