CVE-2026-39373VulnerabilityPublished 29 Apr 2026Updated 16 Sep 2026

SUSE · Security update for python-jwcrypto

Affects SUSESource GCVE Database

Authoritative record:CVE-2026-39373· Medium 5.3

Not known to be exploited · CVSS 5.3 Medium : upgrade SUSE to 9.8 when convenient.

Data as of 26 Oct 2026, 09:16 UTC

CVSS 3.1 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 21% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 9.8

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

Exploitation evidence

Disclosed: evidence found.
CVE published 7 Apr 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.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade redhat/python-jwcrypto to 9.8.

Affected software

Product	Affected	Fixed in
Redhatredhat/python-jwcrypto`pkg:deb/redhat/python-jwcrypto`Other threats	Affected =9 <9.8	Fixed in 9.8

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Red Hat has released official security updates for python-jwcrypto that address this vulnerability. Users should apply the provided patches as described in the Red Hat advisory RHSA-2026:19042. For detailed update instructions, refer to https://access.redhat.com/articles/11258. Since a patch is available and the vendor has rated the impact as low, applying the update is the recommended mitigation.

Description

A security update for python-jwcrypto addresses a vulnerability (CVE-2026-39373) involving weak mitigation against a JWT bomb attack in the deserialize function. This flaw can lead to memory exhaustion when processing crafted compressed JWE tokens. The issue affects certain versions of python-jwcrypto distributed with Red Hat Enterprise Linux 10 and related SUSE products. Red Hat has released patches to fix this vulnerability and rated the security impact as low. No known exploits are reported in the wild.

Impact

The vulnerability can cause memory exhaustion on systems processing maliciously crafted compressed JWE tokens via the python-jwcrypto library. This could lead to denial of service conditions. However, Red Hat rates the security impact as low, and there are no known exploits in the wild at this time.

Summary

CVE-2026-39373 is a vulnerability in python-jwcrypto where the deserialize function's weak mitigation against JWT bomb attacks allows crafted compressed JWE tokens to cause memory exhaustion. This can potentially disrupt service by exhausting system memory during token processing. The vulnerability is addressed by updates released by Red Hat for python-jwcrypto packages included in Red Hat Enterprise Linux 10 and related distributions. The Red Hat advisory classifies the impact as low and provides updated packages to remediate the issue.

CWE-770Allocation of Resources Without Limits or Throttling (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #25
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
Requirements
Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
Architecture and Design
Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V8.1.4 (opens in a new tab)
V13.4.1 (opens in a new tab)
V11.1.4 (opens in a new tab)
Attack patterns
XML Ping of the Death (opens in a new tab)
Exponential Data Expansion (opens in a new tab)
Serialized Data Parameter Blowup (opens in a new tab)
Serialized Data with Nested Payloads (opens in a new tab)
Oversized Serialized Data Payloads (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Sep 2026, 03:26 UTC

WeaknessesCWE-770

Technical details

References

Community reviews

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