Evidence-led vulnerability intelligence · 2026-10-27 01:47 IST

CVE-2026-65627

Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in potatosalad jose (erlang-jose) allows a remote attacker to exhaust a node's memory with a small crafted JWE token. The jose_jwe_zip:uncompress/2 function in src/jwe/jose_jwe_zip.erl decompresses the DEFLATE-compressed plaintext of a JWE that carries the optional zip: DEF header by calling zlib:inflate/2 on the entire attacker-controlled stream, with no bound on the output size or the inflation ratio. Raw DEFLATE reaches ratios around 1000:1 on highly repetitive input, so a few-kilobyte token inflates to hundreds of megabytes or gigabytes in a single call. Decompression runs automatically during decryption through jose_jwe:block_decrypt/2 (JOSE.JWE.block_decrypt/2 in Elixir), before the recipient can inspect or reject the payload. With the common asymmetric key-management algorithms (RSA-OAEP, ECDH-ES) an attacker needs only the recipient's public key to craft such a token, so no authentication or secret material is required. A single small token can exhaust the node's memory and crash the BEAM, denying service to all users. This issue affects jose: from 1.0.0 before 1.11.13.

MEDIUM · 6.9macOS / Apple

Executive briefing

The source record describes: Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in potatosalad jose (erlang-jose) allows a remote attacker to exhaust a node's memory with a small crafted JWE token. The jose_jwe_zip:uncompress/2 function in src/jwe/jose_jwe_zip.erl decompresses the DEFLATE-compressed plaintext of a JWE that carries the optional zip: DEF header by calling zlib:inflate/2 on the entire attacker-controlled stream, with no bound on the output size or the inflation ratio. Raw DEFLATE reaches ratios around 1000:1 on highly repetitive input, so a few-kilobyte token inflates to hundreds of megabytes or gigabytes in a single call. Decompression runs automatically during decryption through jose_jwe:block_decrypt/2 (JOSE.JWE.block_decrypt/2 in Elixir), before the recipient can inspect or reject the payload. With the common asymmetric key-management algorithms (RSA-OAEP, ECDH-ES) an attacker needs only the recipient's public key to craft such a token, so no authentication or secret material is required. A single small token can exhaust the node's memory and crash the BEAM, denying service to all users. This issue affects jose: from 1.0.0 before 1.11.13. The practical risk depends on whether an affected product/version is present, reachable and configured in an exploitable way. Review the affected-product evidence and linked vendor advisories before assigning exposure status.

Assessment: Potential exposure only — validate the installed product, exact version, configuration and vendor applicability before treating an asset as confirmed vulnerable.

Evidence confidence: Limited Evidence-derived, not an exploitability verdict

Severity & attack characteristics

6.9 / 10 · 4.0

CVSS vector:
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack vectorL

Attack complexityL

Attack requirementsN

Privileges requiredN

User interactionN

ScopeX

Technical explanation & impact

The technical mechanism is not expanded beyond the source description unless a referenced advisory supplies additional evidence. Read the linked vendor/CERT advisories for root-cause detail.

Potential impact must be interpreted from the published CVSS impact metrics and the affected component. A CVSS impact score is not proof that a particular asset is exploitable.

Weakness classification

CWE-409

Affected products and versions

NVD has not supplied machine-readable vulnerable CPE product/version entries for this CVE. This is an information gap, not proof that no products are affected. Check the vendor advisory references below.

Remediation & validation

Identify exposure by comparing the affected product and version ranges with your asset inventory, SBOM and externally exposed services.
Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
Validate the remediation with a version check and vulnerability rescan, then retain change evidence.

No fixed version is displayed unless it is explicitly established by a vendor advisory. Follow the vendor's release notes for exact product and branch applicability.

Vendor advisories, patches & exploit references

https://cna.erlef.org/cves/CVE-2026-65627.html REFERENCE 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
https://github.com/potatosalad/erlang-jose/commit/857eb8e7f2d33e2c9ca2189e77226561cacaf2ad VENDOR 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
https://github.com/potatosalad/erlang-jose/commit/a7746ecd4950f85a393136e449a91dac62b5c429 VENDOR 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
https://github.com/potatosalad/erlang-jose/security/advisories/GHSA-wfpv-qxp8-x5gm VENDOR 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
https://osv.dev/vulnerability/EEF-CVE-2026-65627 REFERENCE 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
https://github.com/potatosalad/erlang-jose/security/advisories/GHSA-wfpv-qxp8-x5gm VENDOR 134c704f-9b21-4f2e-91b3-4a467353bcc0

Information gaps & confidence notes

These gaps indicate missing source data. CVE Watch does not fill them with guessed product, exploit or patch details.

NVD does not currently provide machine-readable vulnerable CPE product/version entries for this record.

Last enrichment: 2026-11-03T19:14:54+00:00 · Source last modified: 2026-11-02T22:17:22.133

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