Vulnerability-Lookup

GHSA-49VJ-R7F8-C3P6

Vulnerability from github – Published: 2026-08-10 12:31 – Updated: 2026-08-10 12:31

Details

GNU Emacs for Android contains an off-by-one error in the gvar table parser in src/sfnt.c. The shared-coordinate index boundary check in sfnt_vary_simple_glyph() and sfnt_vary_compound_glyph() uses a strict greater-than comparison instead of greater-than-or-equal, allowing a crafted TrueType variable font to bypass the check and trigger a heap-based out-of-bounds read via memcpy. An attacker can deliver a malicious font file via email, EWW (Emacs Web Wowser), or documents with custom faces, causing Emacs to load it. This exposes heap memory contents which can be later used to defeat ASLR.

This issue was fixed in commit 95ab9ef627b212d74d321c5bbb5b56a1be7b9fbe

Severity

5.3 (Medium)


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

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JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-71391"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-193"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-10T11:17:28Z",
    "severity": "MODERATE"
  },
  "details": "GNU Emacs for Android contains an off-by-one error in the gvar table parser in src/sfnt.c. The shared-coordinate index boundary check in sfnt_vary_simple_glyph() and sfnt_vary_compound_glyph() uses a strict greater-than comparison instead of greater-than-or-equal, allowing a crafted TrueType variable font to bypass the check and trigger a heap-based out-of-bounds read via memcpy. An attacker can deliver a malicious font file via email, EWW (Emacs Web Wowser), or documents with custom faces, causing Emacs to load it.\u00a0This exposes heap memory contents which can be later used to defeat ASLR.\n\n\nThis issue was fixed in commit\u00a095ab9ef627b212d74d321c5bbb5b56a1be7b9fbe",
  "id": "GHSA-49vj-r7f8-c3p6",
  "modified": "2026-08-10T12:31:51Z",
  "published": "2026-08-10T12:31:51Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-71391"
    },
    {
      "type": "WEB",
      "url": "https://cert.pl/en/posts/2026/08/CVE-2026-71391"
    },
    {
      "type": "WEB",
      "url": "https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=95ab9ef627b212d74d321c5bbb5b56a1be7b9fbe"
    },
    {
      "type": "WEB",
      "url": "https://www.gnu.org/savannah-checkouts/gnu/emacs/emacs.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/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",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-71391 (GCVE-0-2026-71391)

Vulnerability from cvelistv5 – Published: 2026-08-10 10:22 – Updated: 2026-08-10 10:22 X_Open Source

Title

Off-by-One Error in GNU Emacs for Android

Summary

Severity

5.3 (Medium)


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

CWE

CWE-193 - Off-by-one Error

Assigner

CERT-PL

References

3 references

URL	Tags
https://cert.pl/en/posts/2026/08/CVE-2026-71391	third-party-advisory
https://www.gnu.org/savannah-checkouts/gnu/emacs/…	product
https://git.savannah.gnu.org/cgit/emacs.git/commi…

Impacted products

1 product

Vendor	Product	Version
GNU	Emacs	Affected: 0 , ≤ 30.2 (custom)

Credits

Michał Majchrowicz (AFINE Team) Marcin Wyczechowski (AFINE Team)

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JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "platforms": [
            "Android"
          ],
          "product": "Emacs",
          "programFiles": [
            "src/sfnt.c"
          ],
          "repo": "https://cgit.git.savannah.gnu.org/cgit/emacs.git",
          "vendor": "GNU",
          "versions": [
            {
              "changes": [
                {
                  "at": "commit 95ab9ef627b212d74d321c5bbb5b56a1be7b9fbe",
                  "status": "unaffected"
                }
              ],
              "lessThanOrEqual": "30.2",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:gnu:emacs:*:*:android:*:*:*:*:*",
                  "versionEndIncluding": "30.2",
                  "versionStartIncluding": "0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ],
          "operator": "OR"
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Micha\u0142 Majchrowicz (AFINE Team)"
        },
        {
          "lang": "en",
          "type": "finder",
          "value": "Marcin Wyczechowski (AFINE Team)"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "GNU Emacs for Android contains an off-by-one error in the gvar table parser in src/sfnt.c. The shared-coordinate index boundary check in sfnt_vary_simple_glyph() and sfnt_vary_compound_glyph() uses a strict greater-than comparison instead of greater-than-or-equal, allowing a crafted TrueType variable font to bypass the check and trigger a heap-based out-of-bounds read via memcpy. An attacker can deliver a malicious font file via email, EWW (Emacs Web Wowser), or documents with custom faces, causing Emacs to load it.\u0026nbsp;This exposes heap memory contents which can be later used to defeat ASLR.\u003cdiv\u003e\u003cbr\u003e\u003c/div\u003e\u003cdiv\u003e\u003cdiv\u003eThis issue was fixed in commit\u0026nbsp;\u003cspan\u003e95ab9ef627b212d74d321c5bbb5b56a1be7b9fbe\u003c/span\u003e\u003c/div\u003e\u003c/div\u003e"
            }
          ],
          "value": "GNU Emacs for Android contains an off-by-one error in the gvar table parser in src/sfnt.c. The shared-coordinate index boundary check in sfnt_vary_simple_glyph() and sfnt_vary_compound_glyph() uses a strict greater-than comparison instead of greater-than-or-equal, allowing a crafted TrueType variable font to bypass the check and trigger a heap-based out-of-bounds read via memcpy. An attacker can deliver a malicious font file via email, EWW (Emacs Web Wowser), or documents with custom faces, causing Emacs to load it.\u00a0This exposes heap memory contents which can be later used to defeat ASLR.\n\n\nThis issue was fixed in commit\u00a095ab9ef627b212d74d321c5bbb5b56a1be7b9fbe"
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "LOW",
            "subIntegrityImpact": "NONE",
            "userInteraction": "PASSIVE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-193",
              "description": "CWE-193 Off-by-one Error",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-10T10:22:17.532Z",
        "orgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6",
        "shortName": "CERT-PL"
      },
      "references": [
        {
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://cert.pl/en/posts/2026/08/CVE-2026-71391"
        },
        {
          "tags": [
            "product"
          ],
          "url": "https://www.gnu.org/savannah-checkouts/gnu/emacs/emacs.html"
        },
        {
          "url": "https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=95ab9ef627b212d74d321c5bbb5b56a1be7b9fbe"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "tags": [
        "x_open-source"
      ],
      "title": "Off-by-One Error in GNU Emacs for Android",
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        "engine": "Vulnogram 1.0.3"
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  },
  "cveMetadata": {
    "assignerOrgId": "4bb8329e-dd38-46c1-aafb-9bf32bcb93c6",
    "assignerShortName": "CERT-PL",
    "cveId": "CVE-2026-71391",
    "datePublished": "2026-08-10T10:22:17.532Z",
    "dateReserved": "2026-08-06T09:25:32.311Z",
    "dateUpdated": "2026-08-10T10:22:17.532Z",
    "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.

Detection rules are retrieved from Rulezet.

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.

Action not permitted

GHSA-49VJ-R7F8-C3P6

CVE-2026-71391 (GCVE-0-2026-71391)

Tags

Sightings

Nomenclature