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CVE-2025-1795: Mishandling of comma during folding and unicode-encoding of email headers

During an address list folding when a separating comma ends up on a folded line and that line is to be unicode-encoded then the separator itself is also unicode-encoded. Expected behavior is that the separating comma remains a plan comma. This can result in the address header being misinterpreted by some mail servers.

LowCVSS 2.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

CPython can incorrectly encode a comma separating email addresses when a long Unicode header is folded across lines. Some mail servers may then interpret the recipient list incorrectly. The documented impact is limited to confidentiality, requires specific formatting conditions, and is rated low severity.

Executive priority

Treat this as routine remediation rather than an emergency. Address it during normal patching, with earlier attention for externally exposed mail-generation services or workflows handling sensitive recipients. Escalation is warranted if testing demonstrates recipient confusion or unintended disclosure in the organization’s mail path.

Technical view

During address-list header folding, a separating comma placed on a Unicode-encoded folded line may be encoded with the surrounding text instead of remaining a plain delimiter. This CWE-116 encoding error can change downstream mail-server parsing. CVSS 4.0 is 2.3, with high attack complexity, additional preconditions, and low confidentiality impact only.

Likely exposure

Exposure is most likely in CPython-based systems that generate folded email address headers containing Unicode and allow a low-privileged party to influence header content. The bundle does not provide clear normalized affected and fixed version ranges, so runtime exposure requires confirmation against Python or operating-system vendor advisories.

Exploitation context

CISA KEV status is false, and the supplied sources do not establish active exploitation. Exploitation requires a particular combination of address-list folding, comma placement, Unicode encoding, and mail-server interpretation, making broad or reliable abuse less likely.

Researcher notes

The core security question is whether malformed serialization causes unintended recipient interpretation by a specific downstream server. Preserve generated headers and receiving-server parsing results during validation. The supplied version data is insufficient to state precise vulnerable or fixed release ranges, although multiple CPython correction commits and a Debian LTS notice are referenced.

Mitigation direction

  • Inventory CPython runtimes used to construct or relay email address headers.
  • Apply vendor-supported Python or distribution updates containing the referenced corrections.
  • Confirm exact fixed versions through Python and operating-system vendor guidance.
  • Prioritize mail systems where low-privileged users influence recipient address headers.

Validation and detection

  • Record deployed Python versions and compare them with current vendor security advisories.
  • Test long Unicode address lists that trigger header folding in a controlled environment.
  • Verify folded separators remain plain commas rather than encoded header content.
  • Confirm representative receiving mail servers interpret every intended address consistently.
Prepared
Confidence
high
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · medium confidence lookup

CWE-116: User-session and phishing behavior lookup

Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2025-1795 mapping review

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Vulnerability profileCVE Program record
Severity
Low
CVSS
2.3 (4.0)
Known Exploited
No
Published

Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
2ADP providers
11Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
2.3CVSS 4.0LowCVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N——PSF

Vulnerability scoring details

Base CVSS 4.0 score

2.3Low
CVSS 4.0 vector shape for CVE-2025-1795Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Python Software FoundationCPython0, 3.10.0, 3.11.0, 3.12.0, 3.13.0a1unaffected
Weakness

CWE details

CWE-116

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-116 · source CWE mapping

Improper Encoding or Escaping of Output

Improper Encoding or Escaping of Output represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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