Vulnerability-Lookup

SUSE-SU-2026:21425-1

Vulnerability from csaf_suse - Published: 2026-04-29 08:14 - Updated: 2026-09-16 19:45

Summary

Security update for python-jwcrypto

Severity

Important

Notes

Title of the patch: Security update for python-jwcrypto

Description of the patch: This update for python-jwcrypto fixes the following issues: - CVE-2026-39373: weak mitigation for JWT bomb attack in the `deserialize` function can lead to memory exhaustion via crafted compressed JWE tokens (bsc#1261802).

Patchnames: SUSE-SLES-16.0-652

CVE-2026-39373

7.5 (High)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

Recommended 2 products

Product	Identifier	Version	Remediation
Unresolved product id: SUSE Linux Enterprise Server 16.0:python313-jwcrypto-1.5.6-160000.3.1.noarch		—	Vendor Fix
Unresolved product id: SUSE Linux Enterprise Server for SAP applications 16.0:python313-jwcrypto-1.5.6-160000.3.1.noarch		—	Vendor Fix

Threats

Impact important

References

8 references

URL	Category
https://www.suse.com/support/security/rating/	external
https://ftp.suse.com/pub/projects/security/csaf/s…	self
https://www.suse.com/support/update/announcement/…	self
https://lists.suse.com/pipermail/sle-security-upd…	self
https://bugzilla.suse.com/1261802	self
https://www.suse.com/security/cve/CVE-2026-39373/	self
https://www.suse.com/security/cve/CVE-2026-39373	external
https://bugzilla.suse.com/1261802	external

JSON

To clipboard

{
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        "text": "This update for python-jwcrypto fixes the following issues:\n\n- CVE-2026-39373: weak mitigation for JWT bomb attack in the `deserialize` function can lead to memory exhaustion via\n  crafted compressed JWE tokens (bsc#1261802).\n",
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          "text": "JWCrypto implements JWK, JWS, and JWE specifications using python-cryptography. Prior to 1.5.7, an unauthenticated attacker can exhaust server memory by sending crafted JWE tokens with ZIP compression. The existing patch for CVE-2024-28102  limits input token size to 250KB but does not validate the decompressed output size. An unauthenticated attacker can cause memory exhaustion on memory-constrained systems. A token under the 250KB input limit can decompress to approximately 100MB. This vulnerability is fixed in 1.5.7.",
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      ],
      "title": "CVE-2026-39373"
    }
  ]
}

CVE-2026-39373 (GCVE-0-2026-39373)

Vulnerability from cvelistv5 – Published: 2026-04-07 19:35 – Updated: 2026-04-07 20:22

Title

JWCrypto: JWE ZIP decompression bomb

Summary

JWCrypto implements JWK, JWS, and JWE specifications using python-cryptography. Prior to 1.5.7, an unauthenticated attacker can exhaust server memory by sending crafted JWE tokens with ZIP compression. The existing patch for CVE-2024-28102 limits input token size to 250KB but does not validate the decompressed output size. An unauthenticated attacker can cause memory exhaustion on memory-constrained systems. A token under the 250KB input limit can decompress to approximately 100MB. This vulnerability is fixed in 1.5.7.

Severity

5.3 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-07 20:22 UTC

CWE

CWE-409 - Improper Handling of Highly Compressed Data (Data Amplification)

Assigner

GitHub_M mitre root Scorecard

References

1 reference

URL	Tags
https://github.com/latchset/jwcrypto/security/adv…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version
latchset	jwcrypto	Affected: < 1.5.7

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-39373",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-07T20:22:50.934916Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-07T20:22:57.790Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "jwcrypto",
          "vendor": "latchset",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.5.7"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "JWCrypto implements JWK, JWS, and JWE specifications using python-cryptography. Prior to 1.5.7, an unauthenticated attacker can exhaust server memory by sending crafted JWE tokens with ZIP compression. The existing patch for CVE-2024-28102  limits input token size to 250KB but does not validate the decompressed output size. An unauthenticated attacker can cause memory exhaustion on memory-constrained systems. A token under the 250KB input limit can decompress to approximately 100MB. This vulnerability is fixed in 1.5.7."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-409",
              "description": "CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)",
              "lang": "en",
              "type": "CWE"
            }
          ]
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-07T19:35:36.071Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/latchset/jwcrypto/security/advisories/GHSA-fjrm-76x2-c4q4",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/latchset/jwcrypto/security/advisories/GHSA-fjrm-76x2-c4q4"
        }
      ],
      "source": {
        "advisory": "GHSA-fjrm-76x2-c4q4",
        "discovery": "UNKNOWN"
      },
      "title": "JWCrypto: JWE ZIP decompression bomb"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-39373",
    "datePublished": "2026-04-07T19:35:36.071Z",
    "dateReserved": "2026-04-06T21:29:17.350Z",
    "dateUpdated": "2026-04-07T20:22:57.790Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

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SUSE-SU-2026:21425-1

CVE-2026-39373 (GCVE-0-2026-39373)

Tags

Sightings

Nomenclature

Related by attack behaviour