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CVE-2026-65626— Bleichenbacher padding oracle in RSAES-PKCS1-v1_5 decryption 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_pkcs1 模块中纯 Erlang 实现的 RSAES-PKCS1-v1_5 解密功能存在 Bleichenbacher 填充预言机漏洞。具体而言，eme_pkcs1_decode/2 函数在解密后的数据块具有有效的 PKCS#1 v1.5 填充格式（即起始字节为 0x00 0x02，后跟至少八个非零字节的填充串，并以 0x00 分隔符结尾）时返回恢复后的明文；否则返回一个不同的错误结果。此外，rsaes_pkcs1_decrypt/2 函数在长度校验失败时还会额外返回 {error, {bads

CVSS 5.9 · Medium
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I. Basic Information for CVE-2026-65626

Vulnerability Information
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Vulnerability Title
Bleichenbacher padding oracle in RSAES-PKCS1-v1_5 decryption in jose
Source: CVE Program / CVE List V5
Vulnerability Description
The pure-Erlang RSAES-PKCS1-v1_5 decryption in the jose_jwa_pkcs1 module is a Bleichenbacher padding oracle. eme_pkcs1_decode/2 returns the recovered message when a decrypted block has valid PKCS#1 v1.5 padding (a leading 0x00 0x02, a padding string of at least eight non-zero bytes, and a 0x00 separator) and returns a distinct error result otherwise, and rsaes_pkcs1_decrypt/2 additionally returns {error, {badsize, _}} when the length check fails. The implementation applies no implicit-rejection countermeasure (RFC 8017 §7.2.2): it does not substitute a deterministic pseudo-random plaintext on a padding failure, so a one-bit padding-conformance signal leaks to the caller. Because the underlying modular exponentiation in dp/2 is a raw, non-blinded crypto:mod_pow/3, the padding check also stays distinguishable by timing even when an application normalizes every failure to a single error value. An unauthenticated attacker who knows only the public RSA key and can submit ciphertexts to a decryption endpoint that unwraps RSA1_5 JWE keys (or otherwise calls decrypt_private/3 with rsa_pkcs1_padding) can use this oracle to recover the plaintext of intercepted ciphertexts, such as content-encryption keys and thus the protected message, or to forge signatures, through roughly 10^4 to 10^6 adaptive chosen-ciphertext queries. This issue affects jose: from 1.3.0 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:H/VI:N/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
通过差异性导致的信息暴露
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
potatosalad jose 1.3.0 ~ 1.11.13 cpe:2.3:a:potatosalad:jose:*:*:*:*:*:*:*:*
potatosalad jose 853c5d4c4c0bd2a7ecb055b237f4284184e176c8 ~ 0eac8cef9aaa48fb6846f4e47a0002dc4a73966d cpe:2.3:a:potatosalad:jose:*:*:*:*:*:*:*:*

II. Public POCs for CVE-2026-65626

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III. Intelligence Information for CVE-2026-65626

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Patches & Fixes for CVE-2026-65626 (1)

Vendor Advisories for CVE-2026-65626 (2)

Other References for CVE-2026-65626 (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-2026-65628 5.9 MEDIUM Infinite recursion (CPU denial-of-service) in JOSE.JWK.shared_secret/2 on mismatched key t
CVE-2026-65625 5.9 MEDIUM Attacker-controlled AES-GCM authentication tag length allows tag forgery in jose
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-203